“They do want to have the anti-missile missiles, as they call them, and we’re going to see if we can make some available,” Trump said at a news conference at the end of the NATO summit in the Hague on Wednesday. “They’re very hard to get.”

The decision by the Pentagon to halt some of the shipments stoked anxiety among Ukraine’s allies in Congress that the country would be left vulnerable to further Russian airstrikes.

“U.S.-made air defense systems, including the Patriot platform, are the centerpiece of Ukraine’s defenses … They work. They save lives every day,” said Rep. Marcy Kaptur (D-Ohio), the Congressional Ukrainian Caucus co-chair. “If this reporting is true, then Mr. Colby …is taking action that will surely result in the imminent death of many Ukrainian military and civilians.”

The munitions are a mix of air defenses and precision weapons that have been flowing to Ukraine for much of the past two-plus years. They include two different streams of support that the U.S. has provided Ukraine, both under the Biden administration. Some come from drawdowns on current stockpiles, with the DOD receiving money to replenish those munitions as quickly as possible. The second comes from the Ukraine Security Assistance Initiative, in which the U.S. funds the purchase of weapons for Ukraine from American defense firms. The money has been used to put weapons under contract for the Ukrainian government.

Money in the fund was obligated by the end of the Biden administration, with deliveries coming whenever the systems are ready. The drawdowns from current stockpiles have continued under the Trump administration, which has been using up the last of the $61 billion in funding to replenish U.S. stocks of weapons and provide billions in aid for Israel and other partners.

The Trump administration has not requested any further aid for Ukraine, though there is enough left over from the Biden administration to last Ukraine several more months, according to an administration official.

A person familiar with the halt of the munitions said that the Pentagon had been dividing them into categories of criticality since February, over concerns that the DOD was using too many air defense munitions in Yemen.