The United States is halting some weapons shipments to Ukraine amid its war with Russia, the White House confirmed Tuesday.

White House spokesperson Anna Kelly told CBS News in a statement that the "decision was made to put America's interests first following" a Defense Department "review of our nation's military support and assistance to other countries across the globe."

A U.S. official told CBS News the move was over concerns about U.S. military stockpiles falling too low.

The Trump administration did not confirm which weapons were being pulled from delivery or the scale of the pullback.

Kelly added, "The strength of the United States Armed Forces remains unquestioned — just ask Iran," in reference to the U.S. strikes last month on three Iranian nuclear facilities.

Elbridge Colby, Defense Department under secretary for policy, said in a separate statement Tuesday night in response to the move that the "Department of Defense continues to provide the resident 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 U.S. forces' readiness for administration defense priorities."

A White House official said Wednesday the pause in shipments to Ukraine is part of a larger review that the Pentagon has been conducting of weapons shipments to all countries that receive them from the U.S. Defense Secretary Pete Hegseth began this review weeks ago at the direction of President Trump. The official said the review was undertaken to ensure the Pentagon under the previous administration was "prioritizing America's needs."

Although the Ukraine pause is what leaked to the media, the White House official said some other countries have been "reclassified" as well, meaning, they have been de-prioritized for receiving weapons and munitions from the U.S. The White House official did not name those countries, or say  how long the pause in some weapons shipments to Ukraine may last. 

The U.S. has provided Ukraine with tens of billions of dollars in military aid since Russia's full-scale invasion of Ukraine in February 2022.

In early March, following a confrontational Oval Office meeting between President Trump and Ukrainian President Volodymyr Zelenskyy, the White House announced it was pausing military aid to Ukraine that had already been earmarked by the Biden administration. It also said it was pausing intelligence sharing to Ukraine.  

The pause on both fronts was lifted about a week later when Ukraine responded positively to talks over a potential ceasefire, which never materialized at the time.

Then, in late April, the U.S. and Ukraine reached a deal that would give the U.S. access to Ukraine's mineral reserves. As part of the tenets of the deal, according to Ukrainian officials, the U.S. would contribute in the form of military assistance to a joint U.S.-Ukraine fund.

Malcolm Chalmers, deputy director-general of the Royal United Services Institute military think tank, told CBS News in March that about 20% of Ukraine's military hardware is supplied by the U.S., with 25% provided by Europe and the rest of the world, and 55% produced in Ukraine.