With only two days before Israel outlaws operations on its soil of the main U.N. aid agency for Palestinian refugees, the United Nations Security Council on Tuesday took up the issue at a meeting where the United States was Israel’s sole defender.

The Israeli laws target a 75-year-old agency that has been a backbone of humanitarian aid delivery to two million Palestinians in Gaza, just as a fragile cease-fire is taking hold there. The agency also helps Palestinians in the Israeli-occupied West Bank and in East Jerusalem.

On Tuesday, senior U.N. officials and every member of the Security Council save the United States called Israel’s actions a violation of its obligations under international law and the U.N. charter. They warned that the restrictions would have a disastrous impact on aid delivery and jeopardize peace in the long-term.

“The legislation makes a mockery of international law and imposes massive constraints,” said Philippe Lazzarini the chief of the aid agency, known as UNRWA. “We are determined, however, to stay and deliver until it is no longer possible to do so.”

The Trump administration’s interim representative to the U.N., Dorothy Shea, dismissed the agency’s claims as exaggerated, and called warnings that aid will come to a halt “irresponsible and dangerous.” She said the United States supported “Israel’s sovereign decision” to close the aid agency’s offices on its soil.

The legislation, passed by the Israeli Parliament in October, also forbids contact between Israel officials and employees of the agency, which is formally known as he United Nations Relief and Works Agency for Palestine Refugees in the Near East.

Israeli officials have accused the agency of being infiltrated by militants from Hamas, the militant group it has been at war with in Gaza since October 2023, when Hamas attacked Israel. The twos sides reached a cease-fire a little over week ago.

UNRWA was formed in the wake of the wars surrounding Israel’s establishment in 1948. Its mandate includes providing food, essential aid, health care, education, shelter and other services to Palestinians around the Middle East who were displaced by that conflict, as well as their descendants.

On Tuesday, the Israeli ambassador to the United Nations, Danny Danon, told diplomats that Israel’s decision to essentially outlaw the group was not a political one but instead was rooted in national security. He said Israel would cooperate with other U.N. agencies.

Mr. Danon informed the U.N. of Israel’s intention to enforce the law in a letter on Friday He told the council that the legislation targeting UNRWA would come into full effect on Thursday. He said the agency “must cease its operation and evacuate the premises it operates in Jerusalem.”

In a response to Israel’s letter, the U.N. secretary general, António Guterres, in a letter on Monday asked Israel to reverse course, said that under international law Israel was obliged to facilitate the work of the agency, not hinder it.

Mr. Guterres said that the premises the aid workers have been ordered to vacate in East Jerusalem are U.N. property that is protected under international law.

At the same time, he said that he took Israeli allegations about ties between UNRWA workers and Hamas very seriously and that he had taken decisive action to address them.

Two U.N. investigations begun in response to Israel complains found that fewer than 10 agency staffers out of 13,000 were affiliated with Hamas. They were fired. The European Union has said Israel failed to show proof for its allegations of broad infiltration and resumed donations to the agency.

Mr. Lazzarini on Tuesday described a pivotal role for his agency in Gaza since the war began. He said it had delivered two-thirds of all food assistance, provided shelter to over a million displaced Palestinians and vaccinated a quarter million children against polio.

Tuesday was not the first time the United States has stood alone at the Security Council in defense of Israel, a close ally. The Biden administration vetoed four cease-fire resolutions at the Security Council, standing by Israel, which said it wasn’t ready to end the war. Another close U.S. ally, Britain, was among the 14 other council members speaking out against the Israeli law.

“The vital work of UNRWA in ensuring that Palestinians have access to education and health care must also be protected in Gaza as well as the West Bank and East Jerusalem,” said Britain’s deputy ambassador, James Kariuki. “These represent the most fundamental of human rights.”

Riyad Mansour, the Palestinian representative to the U.N., told the council that Israel had long worked to dismantle the agency as part of a strategy to strip refugee status away from displaced Palestinians and thus their right to return to their old lands.

“There is no alternative to the Palestinian government, and there is no alternative to UNRWA,” Mr. Mansour said. “Israel does not get to pick and chose who represents the Palestinian people or who represents the U.N.”

Treating H.I.V. across dozens of nations. Stopping the forced labor of Chinese workers. Training Mexican and Colombian police in anti-narcotics enforcement.

Those are just a tiny sample of aid programs around the world operating with grant money from the U.S. government that could be permanently shut down under an executive order President Trump signed last week to halt foreign aid.

The sense of crisis among aid groups worldwide is surging, as American officials tell groups they must obey an almost universal stop-work order issued by Secretary of State Marco Rubio after Mr. Trump’s directive.

The officials say the groups must freeze nearly all programs that have received any of the $70 billion of annual aid budget approved by Congress through bipartisan negotiations. They include programs that provide medicine, shelter and clean water in dire conditions and often make the difference between life and death.

Uncertain of whether they can pay salaries or get any future funding, groups around the world said they are starting to lay off employees or furlough them. In the United States alone, tens of thousands of employees, many of whom live in the Washington area and rely on contract work with U.S. agencies, could lose their jobs. Some have already been laid off.

Leaders of aid groups say they have never seen such an expansive and damaging directive, even during periods of aid reassessment by earlier administrations. Many of them are scrambling to contact lawmakers and other U.S. officials to get urgent messages to Mr. Rubio. They said some programs will be hard to restart after a temporary shutdown, and many could disappear.

The State Department said the move was aimed at ensuring that all foreign aid programs “are efficient and consistent with U.S. foreign policy under the America First agenda.”

The crisis deepened on Monday evening, when Jason Gray, the acting head of the United States Agency for International Development, put about 60 top officials on paid leave. He wrote in an email that those officials had taken actions “designed to circumvent the president’s executive orders.” On Tuesday, office workers removed photographs of leaders from the walls. Contractors have also been fired or put on leave.

Mr. Rubio said in a cable to U.S. missions abroad that the halt would last at least through a 90-day assessment period. But U.S. officials have already told some aid groups that certain programs, including ones that promote diversity, women’s reproductive rights and climate resilience, will be permanently cut.

U.S. agencies will need to break contracts during the halt, and they will likely need to pay fees. Among the U.S.A.I.D. employees put on paid leave are three lawyers, including the lead ethics lawyer, according to one person briefed on the situation.

The executive order halting foreign aid was the president’s first major foreign policy action, and many aid groups are only now understanding its broad scope. Foreign assistance money generally supports humanitarian, development and security programs, and it makes up less than 1 percent of the government budget.

Two Democratic members of the House, Gregory Meeks of New York and Lois Frankel of Florida, sent Mr. Rubio a letter on Saturday saying that lives were being “placed at risk” because of the aid halt. “Congress has appropriated and cleared these funds for use, and it is our constitutional duty to make sure these funds are spent as directed,” they wrote.

The stop order applies to most military and security assistance programs, including in Ukraine, Taiwan and Jordan. Much of that aid is disbursed by the State Department. Military aid to Israel and Egypt is exempted, as is emergency food assistance.

Mr. Trump’s decision to halt foreign aid could cause long-term damage to U.S. strategic interests, critics of the action say. Policymakers from both parties have long regarded foreign aid as a potent form of American power, a way to increase U.S. influence overseas using a tiny budget compared with military spending. Many development programs support democracy, education and civil rights efforts.

In recent years, China has tried to win more global influence with development projects, and it could gain ground as the United States retreats.

“This 90-day stop-work is a gift to our enemies and competitors — with effects that go beyond the immediate harms to people,” said Dr. Atul Gawande, the assistant administrator at U.S.A.I.D. in the Biden administration.

“It trashes our alliances with scores of countries built over half a century, trashes our world-leading expertise and capacity and threatens our security,” he said.

Dr. Gawande noted that U.S.A.I.D. has the largest footprint abroad after the military, employing hundreds of thousands of contractors, who will now be dismissed or put on leave.

Some former officials say a goal of the action could be to dismantle U.S.A.I.D. and move its work to the State Department — while keeping the amount paltry. The Trump appointee at the State Department overseeing foreign aid is Pete Marocco, a divisive figure in the first Trump administration who worked at the Pentagon, State Department and U.S.A.I.D. At the aid agency, employees filed a 13-page dissent memo, accusing him of mismanagement. Senior State Department officials can exercise authority over U.S.A.I.D., though the agency usually operates autonomously.

Some of U.S.A.I.D.’s critical work is listed on its website. One document says that during the civil war in Sudan, a United Nations agency relied on U.S. government support to screen about 5.1 million children age 5 and under for malnutrition, and it provided about 288,000 children with lifesaving treatment last year between January and October.

Smaller groups will struggle to survive. China Labor Watch, a New York-based group with overseas offices that aims to end forced labor and trafficking of Chinese workers, is shutting down programs that rely on $900,000 of annual aid from the State Department, said Li Qiang, the organization’s founder. Seven staff employees will be placed on unpaid leave and could depart for good, Mr. Li said, adding that employees who lose their work visas might have to return to China, where they could be scrutinized by security officers.

Groups worldwide that have relied on U.S. funding are now “victims of this disruption, leading to distrust in the U.S. government,” he said.

He continued: “This will further isolate the U.S. internationally. Damaging national credibility and alienating allies for short-term gains will have lasting repercussions.”

The clampdown also cripples the President’s Emergency Plan for AIDS Relief, or PEPFAR, the celebrated program started by President George W. Bush that is credited with saving more than 25 million lives. A shutdown of the program would likely cost millions of lives in the coming years, health experts said. The program’s work involves more than 250,000 health workers in 54 countries.

“When the funding stops before the epidemic is under control, you erode the investments you’ve made in the past,” said Dr. Linda-Gail Bekker, who heads the Desmond Tutu H.I.V. Center at the University of Cape Town in South Africa.

Simultaneously, Mr. Trump’s decision to withdraw from the World Health Organization has prompted that group to tighten its belt, curtailing travel and limiting operations on the ground.

On Sunday night, employees of the Centers for Disease Control and Prevention were instructed to immediately stop communicating with W.H.O. staff. and other international partners.

The blackout means American officials are likely to lose access to information about human outbreaks, including of mpox, polio and the emerging mosquito-borne disease Oropouche, and animal diseases, like swine flu, that could devastate the nation’s agricultural industry, Dr. Gawande said.

U.S.A.I.D. has helped to contain 11 serious outbreaks of Ebola and other hemorrhagic fevers in the last four years. One such disease, Marburg, is smoldering even now in Tanzania, with 15 confirmed cases and eight probable cases. Ten people have died.

“This is a disease with no test, no treatment and no vaccine that’s been approved,” Dr. Gawande said.

On Monday, Trump administration officials instructed organizations abroad to stop distributing H.I.V. medications that were purchased with U.S. aid money, even if the drugs are already in clinics.

Separately, officials worldwide were told that PEPFAR’s data systems would be shut down on Monday evening and that they should “prioritize copying key documents and data,” according to an email viewed by The New York Times. The system was maintained by a contractor forced to stop work because of the aid freeze.

About 90 percent of Dr. Bekker’s work in South Africa is funded by PEPFAR and the National Institutes of Health. Her team has helped to test H.I.V. medications and preventive drugs, and vaccines for Covid and human papillomavirus, or HPV, all of which are used in the United States.

Shutting down PEPFAR, which accounts for 20 percent of South Africa’s H.I.V. budget, would add more than a half million new H.I.V. infections and more than 600,000 related deaths in the country over the next decade, Dr. Bekker and her colleagues have estimated. The effect is likely to be far worse in poorer countries, like Mozambique, where PEPFAR funds the bulk of H.I.V. programs.

Abruptly halting treatment can endanger patients’ lives, but it can also increase spread of the virus and lead to resistance to the available drugs.

The Trump administration’s actions will cause long-lasting harm, including to Americans, said Asia Russell, executive director of the advocacy group Health Gap.

“If you’re trying to achieve a review of all foreign assistance, including PEPFAR, you can do that without attacking the programs through stopping them,” Ms. Russell said.

“It’s extraordinarily dangerous and perhaps deadly to do it this way,” she said, “but it’s also wasteful and inefficient.”

The world is closer than ever to the apocalypse.

That was the dire assessment issued on Tuesday by the Bulletin of the Atomic Scientists, a nonprofit organization and publication whose signature Doomsday Clock has been estimating — in the stark terms of “minutes to midnight” — how close humanity is to annihilation since 1947.

The organization said that it had moved the clock’s hands closer to that dreaded day — from 90 seconds to midnight to 89 seconds to midnight. It cited the threats posed by nuclear weapons, climate change and the potential misuse of biological science and artificial intelligence — existential dangers it said had been exacerbated by the spread of misinformation, disinformation and conspiracy theories.

“In setting the Clock one second closer to midnight, we send a stark signal: Because the world is already perilously close to the precipice, a move of even a single second should be taken as an indication of extreme danger and an unmistakable warning that every second of delay in reversing course increases the probability of global disaster,” the bulletin said in a statement.

The clock is set by the organization’s Science and Security Board, made up of experts in nuclear technology, global security, climate science and other fields. The clock was created in 1947, when the organization’s concerns revolved around the prospect of nuclear war between the United States and the Soviet Union. The time then was set at seven minutes to midnight.

Since then, the scientists behind the project have broadened their focus to consider other threats like climate change, infectious disease and the spread of misinformation fueled by artificial intelligence. And the clock’s hands have moved back and forth. The last shift was in January 2023, when the clock was changed from 100 seconds to midnight to 90 seconds to midnight, largely because of the war in Ukraine.

The clock was set farthest from midnight in 1991, after the United States and the Soviet Union signed the Strategic Arms Reduction Treaty, designed to scale down their stockpiles of long-lange nuclear weapons. In response, the bulletin moved the clock to 17 minutes to midnight.

The clock did not change during the Cuban Missile Crisis in 1962 because “too little was known at the time about the circumstances of the standoff or what the outcome would be,” the bulletin says on its website.

Critics have dismissed the clock as a stunt based on subjective assessments. Others have said that its repeated warnings of total annihilation could end up being dismissed by the public — the public policy equivalent of the boy who cried wolf.

But the scientists who set the clock call it an internationally recognized symbol and “a reminder of the perils we must address if we are to survive on the planet.”

“The purpose of the Doomsday Clock is to start a global conversation about the very real existential threats that keep the world’s top scientists awake at night,” said Daniel Holz, the chairman of the Science and Security Board and the founding director of the Existential Risk Laboratory at University of Chicago.

This year, the bulletin said that global leaders were failing to confront mounting threats to human survival.

It said that the war in Ukraine, now in its third year, “could become nuclear at any moment because of a rash decision or through accident or miscalculation.” It warned that global nuclear arms controls were “collapsing.”

And it said that the impacts of climate change had increased over the past year, which was almost certainly the hottest on record. The growth in solar and wind energy, the bulletin said, “has been impressive but remains insufficient to stabilize the climate.”

In a clear allusion to President Trump, the organization said: “Judging from recent electoral campaigns, climate change is viewed as a low priority in the United States and many other countries.”

Mr. Trump this month signed an executive order to withdraw the United States from the Paris Agreement, the global pact to fight climate change, as part of a series of actions to promote fossil fuels and to withdraw support for renewable energy.

The bulletin also warned of the spread of bird flu and said that rapid advances in artificial intelligence had “increased the risk that terrorists or countries may attain the capability of designing biological weapons for which countermeasures do not exist.”

Despite the bleak outlook, the bulletin said that there was still an opportunity for the world to move back from the brink of collapse if countries — particularly the United States, China and Russia — work more closely to combat climate change, disease and other threats.

“There is still time to make the right choices to turn back the hands of the Doomsday Clock,” Juan Manuel Santos, the former president of Colombia and a recipient of the Nobel Peace Prize, said on Tuesday at a news conference. “In Colombia, we say, ‘Cada segundo cuenta.’ Every second counts. Let us use each one wisely.”

Britain’s populist party, Reform U.K., was expected to bring in more than $1.25 million dollars at a glitzy fund-raiser on Tuesday, a party official said, an extraordinary amount for a party that six months ago was on the fringe of national politics.

The big-ticket, American-style event was the first major fund-raiser since Nigel Farage took over as party leader and his ideological ally, Donald J. Trump, returned to the White House.

Mr. Farage wants to remake British conservatism, just as Mr. Trump has in the United States. He has pushed the movement to the right with a nationalistic platform that is anti-immigrant and anti-regulation.

For a party that raised less than $200,000 in all of 2023, the turnaround since Mr. Farage became its leader last year has been remarkable. Riding a populist wave that has been felt from Germany to France to Washington, Mr. Farage has catapulted his party from a political sideshow to a well-funded force.

Mr. Farage arrived at Oswald’s, an exclusive members-only club in London’s Mayfair neighborhood, Tuesday and hurried out of the drizzle, past a scrum of journalists. Oswald’s is owned by Robin Birley, a major Reform donor.

The Duke of Marlborough, Charles James Spencer-Churchill, followed shortly behind. Arron Banks, who bankrolled the Brexit campaign, also attended, as did Lady Victoria Hervey and Holly Valance, the former pop star and actor who is married to Reform’s treasurer.

A senior party official said that Reform sold 90 tickets at between £10,000 and £25,000 apiece. That would raise well over £1 million ($1.25 million) for the party. The party official spoke on condition of anonymity because he was not authorized to discuss preliminary accounting.

Reform’s treasurer, the real estate billionaire Nick Candy, has pledged to “secure more money for the party than any other in British political history” and Mr. Farage has openly toyed with accepting donations from Mr. Trump’s donors. The billionaire tech mogul Elon Musk has discussed donating money, Mr. Farage has said.

Unlike in the United States, there are no limits on political donations in Britain. (Political spending, however, is capped.) As rumors of a looming donation from Mr. Musk spread, some British politicians have raised the idea of capping foreign campaign donations.

Reform won a record five seats in Parliament (Mr. Farage’s first win after seven failed attempts) and 14 percent of the vote in last year’s national election. Today, the party is polling ahead of the Conservatives and closing the gap with the governing Labour Party.

Despite the polling gains and sudden influx of cash, Reform has a steep fund-raising hill to climb. Labour raised around £30 million and the Tories about £48 million in 2023, the last full year for which data is available.

Mr. Farage built his political career around opposition to the European Union and immigration, helping to drive the Brexit vote in 2016. While polls show the majority of Britons now believe that leaving the European Union was a mistake, that sentiment has not harmed Mr. Farage’s status.

His fortunes look set to be galvanized by Mr. Trump’s win. Reform claims to be Britain’s fastest growing party, recently surpassing the Conservatives with almost 187,000 supporters paying voluntary membership fees.

Mr. Trump and Mr. Farage have been longtime allies. Mr. Trump heralded Mr. Farage’s election last summer, and Mr. Farage was by his side at Mar-a-Lago on election night as Mr. Trump was voted back into the White House.

Many of Reform’s new key pledges in its 2024 manifesto, or policy platform, echo Mr. Trump’s actions during his first days back in office.

Reform pledged to abandon key climate targets and swing the energy sector back toward oil and gas. The party wants to cut taxes, slash “wasteful” government spending and increase military spending. And it wants to scrap diversity, equity and inclusion initiatives.

Like Mr. Trump, Mr. Farage rallies against “woke” ideology and “transgender indoctrination.”

One of Reform’s most ambitious promises is to eliminate the National Health Service waiting lists in two years by investing in private health care and injecting £17 billion ($21.1 billion) into the public health service — nearly three times more than any other political party has pledged.

But the Institute for Fiscal Studies, an independent research group, said that Reform’s overall tax and spending plans “do not add up” and will cost billions more than claimed.

Last week, Mr. Farage heralded Mr. Trump’s return to power as “the greatest comeback in modern politics” and “joyful to behold.” The Republicans, he wrote in a column for The Telegraph, have “discovered a completely new definition of conservatism.”

“Populism was the winner in the recent elections in America,” he wrote. “Who’s to say it could not be the same in the U.K., too?”