On the battlefields of Ukraine and western Russia, a stalemated war has ground on, with Ukrainian troops defending against Russian progress that can be measured sometimes in mere yards. The cost has been heavy casualties on both sides.
President Trump’s decision this week to pause military assistance and intelligence sharing could reorder the battlefield, either halting the fight or potentially giving Russia a decisive advantage.
With help from Europe, both with arms and intelligence support, Ukraine could continue the fight through the summer without additional American aid. But the loss of one of its most important benefactors will make it easier for Russia to assault Ukrainian lines of defense, analysts say.
“Despite the disadvantage in munitions and forces, Ukrainians have done admirably well in preventing any kind of Russian breakthrough,” Seth G. Jones, a senior vice president with the Center for Strategic and International Studies, said in an interview.
Trump administration officials have suggested that the pause in support could be relatively short-lived if Ukraine’s president, Volodymyr Zelensky, bends to the demands of the White House. Mr. Trump, in his address to Congress on Tuesday night, said he appreciated that Mr. Zelensky had said earlier in the day that he was ready to “come to the negotiating table.”
For now, the Trump administration is putting maximum pressure on Ukraine, and relatively little on Russia’s president, Vladimir V. Putin, or the Russian military, which has continued to attack Ukrainian cities. If the United States is seen as a completely unfair broker of peace, Ukraine could look for ways to continue the fight with the support of Europe.
The Russians still have not established air superiority since invading Ukraine three years ago. They have not effectively managed to combine military units in the joint operations, and have suffered so many casualties that Mr. Putin brought in 11,000 North Korean troops to help relieve the strain, military experts said.
But that was before Mr. Trump threw his weight behind Russia.
“The immediate hit will be on troop morale — bolstering the Russians and depressing the Ukrainians,” said Alexander Vindman, a Ukrainian-born former U.S. Army officer who served on the National Security Council in 2019.
Mr. Trump’s decision affects billions of dollars in arms and ammunition in the pipeline and on order. It halts deliveries of equipment from Pentagon stockpiles as well as aid through the Ukraine Security Assistance Initiative, which provides funds that Kyiv can use to buy new military hardware directly from U.S. defense companies.
Ukraine also stands to lose advanced weapons, including surface-to-surface ballistic missiles, long-range rocket artillery, parts, and maintenance and technical support.
Critically, the pause in U.S. military aid will halt the delivery of interceptor missiles for Patriot and NASAMS air defense systems, which have saved an untold number of lives as they shielded Ukrainian cities from missile and drone attacks.
The intelligence pause will withhold information that Ukraine uses to target Russian forces.
Withholding the aid, according to Trump administration officials, is meant to pressure Mr. Zelensky into signing a deal to give American companies access to Ukrainian minerals. If he makes an agreement, said one Trump administration official, the intelligence sharing will continue and the military supplies already allocated by the Biden administration will flow once more.
But how much new military aid Mr. Trump would be willing to provide is not clear.
Russian forces have been trying to claw back more of the territory in the Kursk region of Russia that Ukraine seized last year, and preparing for more fighting along the main front lines in Ukraine’s eastern Donbas area.
“They’ve been regenerating in place and trying to repair some damage from last fall’s offensive,” said Dara Massicot, a Russian military specialist at the Carnegie Endowment for International Peace. “I would expect another push to begin probably by May.”
Ukraine, which has bolstered its own weapons production, and Europe are not without their own resources.
Europe, in particular France and Britain, supplies Ukraine with satellite imagery that can be used to find Russian targets on the battlefield. Still, European satellites have not been as focused on Russian miliary movements as American spy satellites, and Ukrainian officials concede that if the intelligence pause continues there will be consequences.
And if the halt in deliveries extends beyond early summer, Ukraine would lose its supply of some advanced weapons, including advanced air defense systems, surface-to-surface ballistic missiles, navigation systems and long-range rocket artillery.
A prolonged shortage of those arms would hurt Ukraine’s ability to strike longer-range targets and could make Ukrainian cities and troops more vulnerable to missile, rocket and drone attacks.
The Trump administration has sent some of the weapons the Biden administration promised Ukraine, including “hundreds of Guided Multiple Launch Rocket Systems (GMLRS) and antitank weapons and thousands of artillery rounds,” the Pentagon said on Monday.
Under Mr. Trump’s directive, those deliveries would stop, at least until the president determined that Ukraine had demonstrated a good-faith commitment to peace negotiations with Russia, a senior administration official said.
Still, “the nature of the kinds of weapon systems that the Ukrainians are presently using are different than the ones that they were reliant upon very heavily in the early months of the war,” said George Barros, a Russia expert at the Institute for the Study of War. “The Ukraine defense industrial base has grown significantly, and they could produce a lot of stuff that they need.”
In fact, in recent weeks the pace of Russian assaults has slowed along some of the hottest parts of the front, and Russian troops “have suffered heavy losses during their offensive actions,” Col. Oleksii Khilchenko, a Ukrainian brigade commander in eastern Ukraine, said in a phone interview.
“Assaults that previously involved 10 to 15 soldiers have now been reduced to small group attacks of up to five soldiers,” he said.
Mr. Barros said that most of the casualties Ukrainian troops were inflicting on Russia were caused by homemade drones and other weapons produced in Ukraine.
“So it’s not as if Ukrainians on the front lines are going to be running out of their most basic tools right away,” he said.
But what Ukraine will run out of, he and other experts say, are interceptors for the Patriots, which have aided the country’s air defenses.
European countries have Patriot interceptors, but they would have to sacrifice parts of their own air defense umbrella. That might be a big ask at a time when NATO allies can no longer assume that the United States will help defend them if they are attacked.
European leaders have said that they will convene in Brussels on Thursday with two things on the agenda: how to support Ukraine and how to shore up their own military capabilities.
It was unclear where the Starlink satellite internet service stands in Mr. Trump’s pause. Operated by Elon Musk’s SpaceX, Starlink has been critical to the Ukrainian military since the early days of the war, allowing soldiers to communicate and share information without having to resort to text messages on cellular networks that can more easily be intercepted.
During a tense meeting in the Oval Office last week, Mr. Trump told Mr. Zelensky that he was not in a good position. “You don’t have the cards right now,” Mr. Trump said.
But no one can predict what the pause in aid and intelligence sharing will mean for the war, military officials said.
“To say that the Ukrainians ‘don’t have the cards’ indicates to me that those around POTUS don’t actually understand the nature of war or why men and women are actually willing to fight, even if outnumbered,” said Frederick B. Hodges, a retired lieutenant general and a former top U.S. Army commander in Europe.
Ukraine could win, or at least be in a much better position, if the Europeans deliver the support “they’re capable of delivering,” he said. “And they’ll have done it without the U.S. The result will be lost credibility and lost influence.”
The other scenario — where Russia succeeds in Ukraine — could be even dimmer for the Trump administration, military experts said. A Russian victory could embolden Mr. Putin’s expansionist aims, eventually leading to a major war in Europe.
Mr. Jones, of the Center for Strategic and International Studies, noted that the United States tried in the past to stay out of major-powers wars in Europe, and was unsuccessful.
