A few months ago, Oleh Voroshylovskyi, the commander of a Ukrainian unit tasked with shooting down Russian drones attacking Kyiv, received a coveted American weapon to aid in their mission — a Browning machine gun capable of firing rounds at targets over a mile away.

Not only would it help the unit target Russian drones at higher altitudes, it also symbolized America’s support for Ukraine in the war against Russia.

But after the Trump administration’s announcement on Tuesday of a pause in the delivery of some air defense interceptors and other weapons to Ukraine because of dwindling U.S. stockpiles, Mr. Voroshylovskyi is no longer sure about America’s continued support.

“This will have a serious impact on combat effectiveness,” he said in a telephone interview on Wednesday.

Among the munitions being withheld are missiles for U.S.-designed Patriot air defense systems, precision artillery rounds and other missiles that Ukraine fires from its American-made F-16 fighter jets. Although it is unclear how many weapons were included and how soon the pause will be felt on the battlefield, the signal seems clear: Washington is disengaging from the war.

“Ukraine is no longer a priority, no longer at the center of the U.S. foreign policy,” Solomiia Bobrovska, a member of the Ukrainian defense and intelligence parliamentary committee, said in a telephone interview on Wednesday. “At least Trump is very honest about this with the Ukrainians.”