Hundreds of millions of dollars in U.S. military aid has poured into Ukraine since 2014, but that could soon come to an end.
This, after two senior administration officials confirmed President Donald Trump is considering blocking Ukraine's $250 million annual aid package, which is meant to curb aggression from Russia.
Ukraine has been using the aid to fight an armed separatist movement backed by Moscow.
News of the aid review - first reported by Politico - comes days after Trump, at the Group of Seven Summit in France, said Russia should be allowed back into the G7.
Russia was expelled from the group after it abruptly annexed Crimea from Ukraine in 2014.
(SOUNDBITE) (English) U.S. PRESIDENT DONALD TRUMP, SAYING: "I think it would be better to have Russia inside the tent than outside the tent." Critics say the potential aid cut is an example of Trump capitulating to Russia, an issue that has dogged him ever since U.S. intelligence concluded Russia tried to tip the 2016 election in Trump's favor.
Some members of Congress are already sounding the alarm.
Representative Adam Schiff tweeted that withholding that aid would be destructive to U.S. national security.
Trump officials said the review falls in line with his belief that foreign aid must be justified.
The sources said the aid money for Ukraine was still likely be granted, adding that the final decision will be made by President Trump.