In response to the escalating threat, President Trump confirmed Monday that the U.S. will send additional Patriot air defense missiles to Ukraine. He noted that the European Union would finance the purchase of what he described as "various pieces of very sophisticated" U.S. weaponry.

President Trump opened his remarks alongside NATO Secretary-General Mark Rutte in the Oval Office on Monday by threatening "severe tariffs" against Russia.

Trump's moves underline his growing disenchantment with Russian President Vladimir Putin over the lack of progress in U.S.-led efforts to secure a ceasefire.