CNN  — 

The Trump administration is pausing some weapons shipments to Ukraine, including air defense missiles, following a review of military spending and American support to foreign countries, a senior White House official told CNN.

Defense Secretary Pete Hegseth signed off on the review, which the official noted had been underway for months. It was not immediately clear if military support provided to other countries would be affected.

White House Deputy Press Secretary Anna Kelly said the decision was made “to put America’s interests first.”

Russia welcomed the decision, claiming – without providing any evidence – it was made because the US did not have enough weapons.

“As far as we understand the reason for this decision was empty warehouses, lack of these weapons in warehouses. But in any case, the fewer weapons are supplied to Ukraine, the closer the end of the special military operation,” Kremlin spokesperson Dmitry Peskov told reporters in a phone call, using the Kremlin moniker for Russia’s unprovoked war on Ukraine.

Some US officials insinuated the review of aid to Ukraine was related in part to the Pentagon’s push to focus on China and be prepared for potential future conflict in the Pacific — an issue prioritized by the Pentagon’s policy chief, Elbridge Colby.

“The Department of Defense continues to provide the President with robust options to continue military aid to Ukraine, consistent with his goal of bringing this tragic war to an end. At the same time, the Department is rigorously examining and adapting its approach to achieving this objective while also preserving US forces’ readiness for Administration defense priorities,” Colby said in a statement on Tuesday.

The decision to halt some weapons transfers to Ukraine comes after the country’s president, Volodymyr Zelensky, pleaded with Western allies to bolster its aerial defenses after intensifying Russian airborne attacks.

Russia has in recent weeks launched near-nightly air attacks on Ukraine, involving hundreds of drones and missiles. On Sunday, the Ukrainian military said a pilot was killed after his F-16 fighter jet crashed during a Russian aerial assault.

Following the attack, Zelensky said on social media Ukraine is ready to buy “American systems” to strengthen its air defenses.

Zelensky said Wednesday that the Ukrainian government is trying to clarify the situation.

“All details are being clarified regarding the supply of defense support, including the air defense component. One way or another, we must ensure protection for our people,” Zelensky said during his nightly address to the nation,” the president said during his nightly address to the nation.

Ukraine’s defense ministry said Wednesday that it “has not received any official notifications about the suspension or revision of the delivery schedules for the agreed defence assistance.”

But officials in Kyiv stressed on Wednesday that US weapons played a critical part in the country’s defense.

Ukrainian Foreign Minister Andrii Sybiha said that Ukraine urgently needs to bolster its air defenses as Russia keeps increasing the size and frequency of its aerial attacks against Ukrainian cities.

He said that in June alone, Russia launched over 330 missiles, including nearly 80 ballistic missiles, 5,000 combat drones, and 5,000 gliding bombs against Ukraine.

“It would seem very strange, it would seem inhumane to stop supplying missiles … especially to Patriot systems, which are clearly protecting the civilian population in Ukraine on a large scale,” Mykhailo Podolyak, Ukraine’s presidential office advisor, said.

The US has been the biggest single donor of military aid to Ukraine since Russia launched its full-scale invasion in 2022, supplying Ukraine with air defense systems, drones, rocket launchers, radars, tanks and anti-armor weapons, leading to concerns over dwindling US stockpiles.

But the balance of aid to Ukraine has changed significantly since Trump returned to power, casting doubt over the future of US support for Kyiv.

In April, Europe surpassed the US in total military aid to Ukraine for the first time, with its contribution equaling 72 billion Euros ($84.9 billion), compared with the US’s 65 billion Euros ($76.6 billion), according to data from the Kiel Institute for the World Economy, a German think tank that closely tracks wartime aid to Ukraine.

The shift came after Trump halted all shipments of military aid to Ukraine following a heated Oval Office argument with Zelensky in March. Trump resumed aid flows to Ukraine about a week later.

Last week, during the NATO summit in The Hague, US President Donald Trump suggested Kyiv may see future Patriot missile system deliveries from the US – signaling a possible shift in his thinking about US aid flows to Kyiv.

The Patriots are widely considered among the best air defense systems, particularly in protecting against advanced hypersonic and ballistic missiles.

Ukraine is known to have roughly half a dozen of the US-made Patriot air defense systems, which play a crucial role in its air defense, protecting millions of civilians from Russian missiles.

But Kyiv is at risk of running out of missiles for these systems.

This story has been updated with additional information.

CNN’s Svitlana Vlasova and Anna Chernova contributed to this report.