Before Christmas, a contingent of 105 U.S. Marines who would have been sent to Okinawa were redirected to a new base on the United States territory of Guam instead. The small reshuffling marked a major milestone: This was the first time the Marines cut their head count on Okinawa as part of a deal between Washington and Tokyo to shrink an oversized American military presence on the Pacific island that dates back to World War II.

Under the agreement, 9,000 Marines — just under half the force currently on the island — are eventually supposed to leave. But their departure is already two decades behind the original schedule and may not happen for more than a decade to come, until construction of replacement bases is completed.

Their redeployment was agreed to in a deal signed 12 years ago, the result of negotiations and renegotiations going back to 1995, when three U.S. servicemen raped an Okinawan schoolgirl. That crime touched off mass protests that forced the United States and Japan to agree on shrinking the American bases, which were built after the United States stormed Okinawa during a bloody battle in 1945.

The first iteration of the deal, agreed upon in 1996, was supposed to reduce the burden within five to seven years by building an air base on the northern end of the island to replace an existing one in a crowded city. A generation later, the old airfield remains in use and the new one is at least 12 years from completion.

While some islanders are growing impatient, this state of constant delay seems fine with the governments of both the United States and Japan, who have a big geopolitical reason — the rise of China — for wanting to keep the Marines in place.

“So a dozen years later, only a hundred Marines have moved,” said Christopher B. Johnstone, a former director of Northeast Asia in the Office of the Secretary of Defense who helped lead U.S. negotiations of the current 2013 deal. “Both sides know things aren’t moving forward, but neither side is incentivized to take action.”

The urgency to relocate the Marines has been undermined as China has increasingly made its presence felt with military exercises. Last week, Japan’s Defense Ministry reported tracking four Chinese warships sailing between Okinawa and a nearby island.

The growing Chinese presence is felt in Tokyo and Washington, but also in Naha, the Okinawan capital, where Chinese-speaking tourists crowd Kokusai Dori, the main shopping street. Recent mayoral elections across Okinawa have been swept by conservatives who take a more favorable view of the U.S. bases as a protective presence that also supply much-needed jobs.

While anti-base demonstrations still draw hundreds of shouting protesters, many show up with walking canes. Younger Okinawans are more likely to be found at shopping malls such as the American Village, where they mingle with U.S. personnel and their families.

There are still many Okinawans who are furious at the bases. They blame Tokyo as much as Washington, saying the American presence proves that Japan still views their island — which was an independent kingdom until the 19th century — as little more than an internal colony. The current governor, Denny Tamaki, has been a leading opponent of the bases, but he and his predecessor ended up slowing down the process of reducing the American presence by refusing permits and seeking court orders to block construction of the new airfield. Last month, Japan’s Supreme Court rejected his final lawsuit, clearing the way for building to proceed.

“Keeping the bases places an excessive burden on the people of Okinawa,” said Mr. Tamaki, a former social worker whose father was a U.S. Marine. “The pressure that they put on us, in the form of crime and noise and accidents, is a type of structural discrimination.”

Still, the thinking in the two nations’ capitals has clearly shifted. When the original deal was signed, the United States was unchallenged in the western Pacific. China’s military might now puts Okinawa within easy missile range, and North Korea has also built a nuclear arsenal.

Japan would be on the front line of any conflict in Taiwan, which lies within sight of the southernmost island in the Okinawan chain. In 2022, a Chinese military exercise meant to intimidate the self-ruling island also dropped missiles into waters near Japan.

“We all recognize that the world has changed since the 1990s,” said Kevin Maher, a former U.S. diplomat who was consul-general of Okinawa. “That makes people think, ‘Oh, do the Marines actually have to start moving?’”

Still, Mr. Maher and many other American officials say the current plan remains the best option. Recent incidents like four reported sexual assaults by American servicemen last year underscore the risk of renewed anger at the U.S. bases, and Tokyo has little stomach for reopening a tortuously negotiated deal.

Japan’s prime minister, Shigeru Ishiba, repeated his commitment to the current plan during a meeting last week with President Trump, according to Japan’s foreign ministry. Mr. Ishiba has previously said that the gap left by the departing Marines could be filled by Japanese forces or joint bases.

“We will continue to work on reducing the base burden,” Mr. Ishiba said last month during the equivalent of a state-of-the-union speech. But he added that “as the balance of power in the region undergoes a historic shift, we must continue to secure the United States’ regional commitments.”

Japan is not rushing to complete the relocation, whose centerpiece remains the new airfield at Camp Schwab, a U.S. installation an hour north of the existing air base that it will replace.

The coral-filled waters off Camp Schwab are now busy with big barges, which are creating an area of landfill five times larger than the Pentagon building. V-shaped runways here will one day host helicopters and Osprey rotating-rotor airplanes, relocated from the Marine Corps Air Station Futenma in the dense residential neighborhoods in the city of Ginowan.

During a visit to Okinawa in December to mark the relocation of the first Marines, Japan’s defense minister at the time said the airfield will not be ready for use until at least 2036 — 40 years after the first agreement to build it.

The slow progress reflects Japan’s overall lack of urgency, said Hiromori Maedomari, a professor at Okinawa International University who teaches about issues raised by the military bases. “Japan wants to keep the status quo of the Marines in place as long as possible, even if that means Okinawa is expendable,” he said.

Other parts of the relocation plan are only now entering full swing.

At Camp Foster on the southern half of the island, two dozen cranes are building a new headquarters, schools and housing, part of a plan to concentrate Americans on this base, allowing other bases to close.

“It’s finally happening,” said Col. Leroy Bryant Butler, a Marine managing the building projects. “We haven’t seen this level of construction here since the 1950s, when these bases were built.”

Marines will also move to bases in Okinawa’s north, away from crowded population centers. About two-thirds of the U.S. bases in the southern part of the island will eventually be vacated, including a logistics hub filled with warehouses, a seaport and the Futenma air base.

Japan’s cost for the construction is about $1.5 billion a year. That’s in addition to the $2.8 billion that Tokyo spent to build a new base on Guam, Camp Blaz, which opened last month and is supposed to house about half of the Marines who leave Okinawa.

However, the Marines have made no secret of their reluctance to reduce their forces, and decline to provide a timetable. If a conflict breaks out, infantry in Guam would likely have to fight their way back to Japan against a foe who can challenge American air and sea superiority.

“Japan is now in the weapons-engagement zone,” said Wallace Gregson, a retired Marine lieutenant general who commanded the Marine force on Okinawa. “We need to change the conversation to problems that are relevant in 2025.”

Kiuko Notoya contributed reporting.

The United States has stepped up secret drone flights over Mexico to hunt for fentanyl labs, part of the Trump administration’s more aggressive campaign against drug cartels, according to U.S. officials.

The covert drone program, which has not been previously disclosed, began under the Biden administration, according to U.S. officials and others familiar with the program.

But President Trump and his C.I.A. director, John Ratcliffe, have repeatedly promised more intense action against Mexican drug cartels. Increasing the drone flights was a quick initial step.

The C.I.A. has not been authorized to use the drones to take lethal action, the officials said, adding that they do not envision using the drones to conduct airstrikes. For now, C.I.A. officers in Mexico pass information collected by the drones to Mexican officials.

The flights go “well into sovereign Mexico,” one U.S. official said.

The Mexican government has taken steps to address the Trump administration’s concerns about fentanyl, deploying 10,000 troops to the border this month to thwart smuggling. But the Trump administration wants Mexico to do more to destroy or dismantle fentanyl labs and to seize more of the drug.

The drones have proved adept at identifying labs, according to people with knowledge of the program. Fentanyl labs emit chemicals that make them easy to find from the air.

However, during the Biden administration, the Mexican government was slow to take action against labs identified by the Americans, although it did use the information to make arrests, according to two of the officials.

The officials all spoke on the condition their names not be used so they could discuss a classified intelligence program and sensitive diplomacy between Mexico and the United States.

The surveillance flights have already caused consternation in Mexico, which has long been wary of its northern neighbor after multiple U.S. invasions and land grabs.

In addition to the C.I.A.’s efforts, the U.S. military’s Northern Command is also expanding its surveillance of the border. But the U.S. military, unlike the spy agency, is not entering Mexican airspace.

So far, Northern Command has conducted more than two dozen surveillance flights over the southern border using a variety of surveillance aircraft including U-2s, RC-135 Rivet Joints, P-8s and drones, said a senior U.S. military official, who spoke on the condition of anonymity to discuss operational matters.

The military has also created a special intelligence task force of 140 analysts, located near the border, to analyze the information being collected by the surveillance flights and other sources, Northern Command said in a statement this month.

Gen. Gregory M. Guillot, the head of the Northern Command, told the Senate last week that analysts are providing intelligence that “gets after the cartel networks that drive the production and distribution of fentanyl and pushes it across the border.”

In response to questions from lawmakers, General Guillot said the intelligence was shared with Mexican officials to help them “address the cartel violence in terms of sending more troops.” General Guillot said his command had increased intelligence collection in order to make “rapid progress against this threat.”

Asked about General Guillot’s comments, President Claudia Sheinbaum of Mexico said that Mexican sovereignty was “not negotiable, and we will always coordinate without subordinating.”

Officials from the White House, the C.I.A. and the Pentagon all declined to comment on the secret intelligence program.

Mr. Trump signed an executive order on Jan. 20 calling for a crackdown on major cartels. This week, his administration plans to designate a half-dozen cartels and criminal groups in Mexico as foreign terrorist organizations.

The designation gives the U.S. government broad powers to impose economic sanctions on groups and entities linked to them. But the cartels are already under heavy sanctions by the U.S. government, and a foreign terrorist designation would provide no significant new tools to block their financial maneuvering, according to former American officials who have worked on these issues.

While the sanctions are not necessary for the stepped-up intelligence collection by the C.I.A., several former officials said the designation was an important symbolic step that could, eventually, be followed by expanded operations by the U.S. military or intelligence agencies.

The U.S. military’s Seventh Special Forces Group began a training exercise in Mexico this month. Maj. Russell Gordon, a spokesman for First Special Forces Command, said the training with the Mexican Marine Infantry was preplanned and part of “longstanding U.S.-Mexico defense cooperation.”

Still, former officials say they believe that the U.S. military and intelligence agencies are likely to increase training with Mexican authorities in the coming months.

Conducting an airstrike on fentanyl labs would probably cause catastrophic fatalities, as they are often inside homes in urban areas, a person familiar with the program said, most likely contributing to the reluctance to authorize lethal force.

The possibility for violence also exists if the Mexican military or police move against the lab.

But the purpose of providing the intelligence to Mexican authorities is not to kill cartel members, but instead to disable the labs, according to American officials briefed on the program.

If the cooperation and intelligence sharing do not lead to the destruction of the labs, the Trump administration has signaled it is considering alternative moves.

In a visit to the southwestern border this month, Defense Secretary Pete Hegseth did not rule out conducting cross-border raids to pursue cartels inside Mexico.

“All options are on the table,” Mr. Hegseth told reporters.

In the transition to the new Trump administration, a former senior U.S. official said incoming aides had made clear that they planned to use the full American counterterrorism apparatus — surveillance aircraft and satellites, intelligence analysts, as well as American personnel or military contractors — to go after the cartels inside Mexico.

Ms. Sheinbaum, Mexico’s president, has been grilled by reporters about the expanded military flights on the border, after they were detected on Jan. 31.

Last week Mexico’s defense secretary, Gen. Ricardo Trevilla Trejo, told reporters that the military had not received any request from the United States to fly in Mexican airspace and insisted that the surveillance flights had not violated international law as they flew above international waters.

Days later, as more surveillance flights were detected along the border, Ms. Sheinbaum said that the flights were not new, suggesting that they took place under Mr. Biden, but did not elaborate. She said the flights were “part of the dialogue, the coordination, that we have.”

Mr. Trump has announced a former C.I.A. paramilitary officer, Ronald Johnson, as his choice to serve as ambassador to Mexico. Former officials said they believed Mr. Johnson was tapped because of his experience working with both the spy agency and military Special Operations forces.

The president also announced this month that he would appoint Joe Kent, a former Army Green Beret and C.I.A. paramilitary officer, as director of the National Counterterrorism Center.

Mark Mazzetti contributed reporting from Washington, and Emiliano Rodríguez Mega from Mexico City.

Numerous programs aimed at averting violence, instability and extremism worsened by global warming are ensnared in the effort to dismantle the main American aid agency, U.S.A.I.D.

One such project helped communities manage water stations in Niger, a hotbed of Islamist extremist groups where conflicts over scarce water are common. Another helped repair water-treatment plants in the strategic port city of Basra, Iraq, where dry taps had caused violent anti-government protests. The aid group’s oldest program, the Famine Early Warning Systems Network, ran a forecasting system that allowed aid workers in places like war-torn South Sudan to prepare for catastrophic floods last year.

The fate of these programs remains uncertain. The Trump administration has essentially sought to shutter the agency. A federal court has issued a temporary restraining order. On the ground, much of the work has stopped.

“They were buying down future risk,” said Erin Sikorsky, director of the Center for Climate and Security and a former U.S. intelligence official. “Invest little today so we don’t have to spend a lot in the future when things metastasize.”

The German government this week released a report calling climate change “the greatest security threat of our day and age,” echoing a U.S. intelligence report from 2021, which described climate hazards as “threat multipliers.”

Some U.S.A.I.D. funding supported mediation programs to prevent local clashes over land or water. For instance, as the rains become erratic in the Sahel, clashes between farmers and cattle herders become more frequent.

Other U.S.A.I.D. funds supported job training to give young people alternatives to being recruited by terrorist organizations. One such program in Kenya offered motorcycle-repair training. Other programs funded research into crop seeds that could withstand disease and drought, including new varieties of coffee for the global market.

Climate change adds to the pressures facing vulnerable countries. The burning of fossil fuels has raised the average global temperature since the start of the industrial age, and it has supersized extreme weather events such as droughts, floods and storm surges worsened by rising seas. This has, in turn, intensified water shortages, hampered food production and led to increased competition for resources.

The U.S. National Intelligence Council concluded in 2021 that “climate change will increasingly exacerbate risks to U.S. national security interests as the physical impacts increase and geopolitical tensions mount about how to respond.”

The report identified specific flash points, including cross-border water tensions, and said some countries could experience instability, including from straining food and energy systems. It identified nearly a dozen particularly vulnerable countries, including Niger, Chad and Ethiopia. “Building resilience in these countries and regions would probably be especially helpful in mitigating future risks to U.S. interests,” it said.

That was increasingly the goal of several U.S.A.I.D. projects — to help people cope with climate shocks. .

In Kenya, amid six cycles between 2022 and 2024 of rains that failed to arrive on time, U.S.A.I.D. projects helped local farmer cooperatives get fast-growing seeds that could grow with little water: amaranth, beans, green gram. The orders to stop this work, aid workers said, would be felt immediately.

“People will be measurably less able to cope with climate shocks,” said one aid-agency staff member who asked not to be identified out of concern over retaliation against the aid group. “In some cases, people will die of hunger.”

When a drought was forecast in Ethiopia, U.S.A.I.D. projects helped vaccinate animals and encouraged pastoralist communities to sell their animals while they were still healthy. Several agricultural researchers in American universities received U.S.A.I.D. money to develop more nutritious, higher-yielding seeds that could better withstand heat and unpredictable rains.

Water programs were a big part of U.S.A.I.D.’s climate-resilience portfolio. In Basra, where anti-government riots broke out after contaminated water led to the hospitalization of more than 100,000 people, the agency funded the repair of water treatment plants. In Central Asia, the agency devoted $24.5 million to get five countries to cooperate on their shared water sources.

In southwestern Niger, the agency helped craft agreements on how cattle-grazing corridors and water wells could be managed peacefully. In Benin, a program brought together farmer and pastoralist communities to spread the word about looming dry spells because drought meant herders would sometimes bring their animals to graze on other people’s farms, and conflicts would get out of hand.

Ann Vaughn, a former deputy assistant administrator at U.S.A.I.D., said she was most worried about regions where water insecurity could drive unrest and prompt U.S. rivals to exploit the crisis. “With everything going on in the Middle East,” she said, “you add in things like taps not turning on and you don’t have the right seeds, that creates a lot of tension.”

Khalil al-Hayya, Hamas’s chief negotiator, said in a speech on Tuesday that militants intend to hand over the remains of four Israeli hostages to Israel on Thursday in exchange for the release of Palestinian prisoners.

Mr. Hayya said members of the Bibas family would be among the four bodies handed over to Israel on Thursday. The three remaining members of the Bibas family in Gaza include Shiri Bibas and her two children.

Israeli officials said earlier on Tuesday that they expected the remains of Israeli hostages to be returned to Israel on Thursday, though they did not specify that members of the Bibas family would be among them.

Hamas will also increase the number of living hostages scheduled to be released on Saturday to six from three, Mr. al-Hayya said.