For years, the Palestinian administration in the occupied West Bank has doled out hundreds of millions of dollars in stipends to the families of Palestinians jailed or killed by Israel — including those involved in violent attacks.

The United States and Israel have long condemned the payments and pressured the Palestinian Authority to end them. And on Monday, the Authority announced that it was backing away from the practice — a shift that analysts saw as an attempt to curry favor with President Trump and bring much-needed foreign aid into Palestinian coffers.

Palestinian officials, speaking on condition of anonymity to discuss a sensitive issue, said the move was aimed to bring the Palestinian administration into compliance with American law and to allow for more foreign aid to flow. A U.S. law banned direct American economic assistance to the Palestinian Authority as long as it carried out the practice.

The ban has only deepened the economic distress of the cash-strapped Palestinian Authority in recent years and it has increasingly struggled to make ends meet and to pay its employees’ monthly salaries.

Mahmoud Abbas, the aging Palestinian Authority president, issued a decree on Monday night that overhauled the payment system. The stipends have been one of the most emotionally charged issues in Palestinian politics.

A body set up to manage social welfare payments to needy Palestinians, known as the Palestinian National Economic Empowerment Institution, said in a statement that the families of prisoners would receive funds based only on financial needs and social welfare criteria, “without regard to political affiliations or past actions.”

The law means that the families of prisoners would still be eligible for social welfare payments as long as they demonstrate a financial need, as opposed to being compensated for fighting against Israel’s rule.

The new system would abide by 43 internationally recognized criteria for assessing social welfare needs, the statement said.

Both U.S. and Israeli officials will closely monitor the implementation of the new policy to see whether it leads to a genuine shift.

Palestinians were quick to criticize Mr. Abbas’s decision. Many in the West Bank and Gaza view those imprisoned by Israel as either the victims of fundamentally unjust Israeli military courts or freedom fighters who fought back against their occupiers.

But Mr. Abbas is gambling on a new beginning with Mr. Trump after years of bad blood, and he is hoping for a muted domestic response, said Ibrahim Dalalsha, a Palestinian political analyst.

“This is the Trump effect. The Palestinian Authority wants to start off well with Trump,” Mr. Dalalsha said in a phone interview.

Since the U.S. election in November, Mr. Abbas’s government has sought to rebuild its relationship with the American president after his tumultuous first term. But Mr. Trump’s recent insistence that the roughly two million Palestinians should be transferred out of the Gaza Strip has already added new strains.

During his first term, Mr. Trump outraged the Palestinian leadership by moving the U.S. Embassy in Israel from Tel Aviv to the contested capital of Jerusalem, freezing most aid and peddling a peace plan they saw as deeply slanted in Israel’s favor.

Israel has argued that paying benefits to the families of prisoners who have been involved in deadly stabbings, shootings and suicide bombings against Israelis creates a financial incentive for terrorism. It has labeled the policy a “pay-for-slay” arrangement, in which Palestinians with longer sentences get higher stipends, effectively rewarding people for committing deadlier attacks in Israel’s view.

In response, Israel has withheld funds from the Palestinian Authority, often more than $100 million each year. The money is drawn from tax revenues Israel collects on behalf of the Palestinian administration.

In 2018, Mr. Trump signed the Taylor Force Act, which ended economic assistance that directly benefited the Palestinian Authority as long as it continued to disburse the stipends. In its statement, the new Palestinian welfare institution said the reform “aligns directly with the goals of the Taylor Force Act.”

The Israeli government quickly dismissed Mr. Abbas’s announcement as a sham, saying it would not end the practice of paying the families of prisoners.

“This is a new deception scheme by the Palestinian Authority, which intends to continue paying terrorists and their families through alternative payment channels,” said Oren Marmorstein, a spokesman for the Israeli foreign ministry.

Mr. Abbas’s decree was unlikely to immediately lead American aid to begin flowing again to the Palestinian Authority. Mr. Trump has yet to say publicly whether he is willing to support the Palestinian Authority.

And other legal hurdles would remain, including the extended process of certifying that Mr. Abbas’s government is in compliance with the Taylor Force Act.

If the Palestinian Authority enforces the changes, it would be a remarkable about-face for Mr. Abbas, who had previously insisted that he would never give up on the payments. In the past, he has gone so far as to say that even if the Palestinian Authority was running out of money, he would spend whatever remained on the stipends.

In late January, Hussein al-Sheikh, a top adviser to Mr. Abbas, informed Steve Witkoff, Mr. Trump’s Middle East envoy, that the Palestinian Authority was prepared to move ahead with revising its prisoner payments system, according to the Palestinian official and another diplomat.

The shift immediately prompted criticism in the West Bank, where the Palestinian Authority administers some areas, including major Palestinian cities. Hamas and Islamic Jihad, Mr. Abbas’s rivals, also condemned the decision.

Qadura Fares, the Palestinian Authority’s commissioner for prisoners’ affairs, called on Mr. Abbas to “immediately retract” the decree during a news conference on Tuesday.

“This move is deeply wrong,” said Esmat Mansour, a former prisoner who said he had served 20 years in prison for involvement in a stabbing attack against an Israeli. “The prisoners are icon. They are the ones who have sacrificed for our freedom.”

Natan Odenheimer and Fatima AbdulKarim contributed reporting to this article.

President Trump insisted Tuesday that the United States has the authority to “take” Gaza and that other countries in the region will absorb the Palestinians who currently live there, speaking as he sat beside Jordan’s king in the Oval Office.

“We will have Gaza,” Mr. Trump said. “It’s a war-torn area. We’re going to take it. We’re going to hold it. We’re going to cherish it.”

The remarks — made at an impromptu gaggle with reporters called in abruptly at the start of the bilateral meeting between the two leaders — represented a new form of pressure on King Abdullah II, who sought to praise Mr. Trump as a force for peace in the region while avoiding comment on a barely formed proposal that the president has repeatedly floated in the past week.

Their meeting, along with Jordan’s Crown Prince Hussein, came a week after Mr. Trump declared that he wanted the U.S. to seize control of Gaza and wanted Jordan and Egypt to resettle the roughly two million Palestinians who would be displaced.

Both Jordan and Egypt rejected the idea when Mr. Trump raised it last week at a news conference with Israel’s prime minister, Benjamin Netanyahu, But on Tuesday, King Abdullah largely demurred when asked by reporters about the prospect of forcibly displacing Gazans to allow the United States to take over the territory.

Rather than push back on Mr. Trump’s proposal, King Abdullah said the two nations should consult with other Arab nations, including Egypt.

“I think the point is, how do we make this work in a way that is good for everybody,” King Abdullah said. “Obviously we have to look at the best interests of the United States, of the people in the region, especially to my people of Jordan.”

The meeting with King Abdullah amounted to not only a pivotal moment for a key ally in the Middle East but more broadly for the future of Gaza and the roughly two million Palestinians who call it home.

Mr. Trump in recent days has dug in on his improbable proposal to permanently resettle most Palestinians to Jordan and Egypt, while the United States would be handed control of the territory by Israel and then redevelop it into a hub for jobs and tourism.

Officials in both Jordan and Egypt have rejected the forced displacement of Gazans, which scholars have said would amount to a violation of international law and ethnic cleansing. Mr. Trump, however, ramped up pressure on Egypt and Jordan on the eve of King Abdullah’s visit when he said he could cut aid to Jordan unless it took in Palestinians.

Mr. Trump has privately been talking about the notion of the United States taking control of Gaza for several weeks, according to multiple people who have spoken with him.

King Abdullah now faces the difficult task of trying to protect the more than $1.5 billion in foreign aid Jordan receives from the United States while also trying to get Mr. Trump to back off his demands for the mass removal of Palestinians.

More than half of King Abdullah’s 12 million subjects are of Palestinian descent. Jordan is already home to approximately 700,000 refugees, most of them Syrians who fled from that country’s civil war. The monarchy is concerned that accepting an influx of another roughly two million refugees could inflame tensions between citizens of Palestinian descent and those who are not, analysts say.

Mr. Abdullah could try to convince Mr. Trump that his hope to move Palestinians out of Gaza would complicate his administration’s broader efforts to get Saudi Arabia to join Mr. Trump’s 2020 Abraham Accords, which established formal ties between Israel and four Arab countries.

The fragile cease-fire truce between Hamas and Israel also hung over the meeting after the militant group threatened to delay the release of some hostages on Saturday if Israel did not send more aid to Gaza. Hamas has accused Israel of breaking a promise of sending hundreds of thousands of tents into Gaza, a claim that three Israeli officials and two mediators said were accurate. Mr. Trump responded by threatening “all hell” if Hamas did not release every hostage

President Trump’s proposal for the United States to take over Gaza and remove some two million Palestinians who live there would unquestionably be a severe violation of international law, experts say. As further details of his proposal emerge, the list of potential violations becomes even clearer.

In a Fox News interview on Monday, Mr. Trump said that under his plan, Gaza’s Palestinians would not be allowed to return to the territory, a violation in its own right of an important principle of international law, as well as a component of other international crimes.

His latest comments undermine his aides’ attempts to walk back his initial proposal by claiming he was actually suggesting a temporary, voluntary evacuation of Gaza’s population — a scenario that could have been legally defensible.

“Trump is just casually making major international crimes into policy proposals,” said Janina Dill, the co-director of the Oxford Institute for Ethics, Law and Armed Conflict. “He just normalizes violating, or proposing to violate, the absolute bedrock principles of international law.”

Forced deportation

The forced deportation or transfer of a civilian population is a violation of international humanitarian law, a war crime and a crime against humanity.

The prohibition has been a part of the law of war since the Lieber Code, a set of rules on the conduct of hostilities that dates back to the U.S. Civil War. Forced deportation is also prohibited by multiple provisions of the Geneva Conventions, which the United States has ratified, and the Nuremberg Tribunal after World War II defined it as a war crime.

The Rome Statute that established the International Criminal Court lists forcible population transfers as both a war crime and a crime against humanity. And if the displacement targets a particular group based on their ethnic, religious or national identity, then it is also persecution — an additional crime.

(Because the International Criminal Court recognizes a state of Palestine as a party to the court, it has jurisdiction over those crimes if they take place within Gaza. That is true even if they are committed by citizens of the United States, which has never adopted the Rome Statute and so is not a member of the court.)

When Mr. Trump was asked during a Feb. 4 news conference how much of Gaza’s population he wanted to move, he said, “all of them,” adding, “I would think that they would be thrilled.” When he was pressed on whether he would force them to go if they did not want to, he said, “I don’t think they’re going to tell me no.”

U.S. allies and foes around the world, including France, Germany, Ireland, Spain, Turkey, Russia, and China, immediately and unequivocally condemned Mr. Trump’s proposal. “In the search for solutions, we must not make the problem worse,” said António Guterres, the U.N. secretary general. “It is vital to stay true to the bedrock of international law. It is essential to avoid any form of ethnic cleansing.”

The right to return

Mr. Trump’s response to Fox News, saying that he did not plan to allow Gaza’s population to return, nullifies what otherwise might have been the strongest legal defense of his plan: It is legal under the laws of war to temporarily evacuate civilians for their own safety.

Even with a cease-fire in place, Gaza remains extremely dangerous to civilians because of unexploded bombs, many of them hidden beneath rubble or underground, as well as catastrophic damage to civilian necessities like shelter, water, and power.

However, Mr. Trump made clear on Tuesday that he does not intend to allow the Gazan population to return, even after those dangers have been cleared and the territory is once again safe, which would mean his plan could not be legally justified as a temporary safety measure.

The “right of return,” the principle that all people have the right to enter their own country, is enshrined in multiple treaties, including the International Covenant on Civil and Political Rights, which the United States has signed and ratified.

That principle has also been one of the most contentious issues of the Israeli-Palestinian conflict.

Israel has refused to allow the return of the approximately 700,000 Palestinians who fled or were forced out during the 1948 war that followed the creation of an independent Jewish state — a mass displacement that the Palestinians refer to as the “nakba,” or catastrophe.

The question of whether those refugees and their descendants, now numbering in the millions, will be permitted to return to the territory that is now Israel has been one of the thorniest points of negotiation in the decades of peace talks that have sought to resolve the conflict.

In addition, right-wing Israelis have waged a decades-long effort to build settlements within the West Bank and Gaza in order to lay claim to that land as part of Israel rather than a future Palestinian state.

Seizure of territory

On Sunday, Mr. Trump reiterated his proposal for the United States to take over Gaza, telling reporters on Air Force One that the strip of land was “a big real estate site” that the United States was “going to own.”

It would be a severe violation of international law for the United States to permanently take over the territory of Gaza. The prohibition against a nation forcibly annexing territory is one of the most important and foundational principles of international law.

“There’s a clear rule,” said Marko Milanovic, a professor of international law at the University of Reading in England. “You cannot conquer someone else’s territory.”

It is rare for states to violate that rule. When they have, as in the case of Russia’s invasion of Ukraine, they have tended to claim at least some pretense of legality. Russian President Vladimir Putin claimed that the invasion was necessary to protect the Russian-speaking population of eastern Ukraine from genocide by the Ukrainian government. Although that assertion was false, it paid lip service to the deeper principle that annexation for its own sake would be illegal.

In the case of Gaza, the specifics of that violation would depend partly on whether Palestine is considered a state, said Marko Milanovic, a professor of international law at the University of Reading in England. The United Nations recognizes Palestine as a permanent observer state, and 146 out of 193 U.N. member states recognize Palestinian statehood, but the United States and Israel do not.

But even if Gaza is not considered part of a state, U.S. annexation of the territory would still violate the civilian population’s right to self-determination. The International Court of Justice has ruled twice that the Palestinian people are entitled to that right within Gaza.

“If you take it without their consent, you’re violating their right to self-determination,” Professor Milanovic said. “There’s really no doubt about that.”

The role of international law

Mr. Trump seemed unconcerned with how his proposal might be viewed by the institutions that underpin the international legal system, and he has shown disdain for those institutions.

Last week, he announced sanctions against the International Criminal Court. On Tuesday, he signed an executive order calling for a general review of U.S. funding for and involvement in the United Nations, raising questions about the U.S. commitment to that global body. He also withdrew the United States from the U.N. Human Rights Council.

Even if Mr. Trump’s Gaza plan ultimately does not move forward, his attitude toward international law could have serious consequences for U.S. interests around the world.

By appearing to disregard the value of those rules, Mr. Trump could send a message that he is not strongly committed to defending them in other contexts, such as a potential Chinese invasion of Taiwan, Professor Dill said.

“If we live in a world where conquest is normalized and the legal rule is simply set aside, we live in a completely different world, in a world that’s incredibly dangerous also for Americans,” she said.