At the heart of the impeachment saga that ended on Wednesday in Donald Trump's acquittal was $391 million in U.S. military assistance for Ukraine that the U.S. president ordered be withheld.

But that aid package, which was eventually released last September, wasn't the only U.S. arms transfer meant for the war-torn country that was held up. Several direct commercial sales of arms and ammunition to Ukraine faced significant delays at the same time – and they remain mysteriously frozen months later, BuzzFeed News has learned. Now, after a lengthy wait and down payments in the tens of millions of dollars for the equipment, Kyiv wants its money back.

The Trump administration is currently withholding approval for at least six commercial orders for arms and ammunition from U.S. companies to Ukraine, together worth roughly $30 million, according to three current Ukrainian officials and a former senior U.S. official who have direct knowledge of the sales, straining an already fragile relationship between the two countries. All four officials said that five of the pending sales from U.S. companies have been delayed for around a year, and one of the sales has been held up for more than a year. The officials said they haven't been able to get any answers from the Trump administration about why the deals, which typically take around two months to approve and must be licensed by the State Department, haven't received approval.

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"It might be wise for the Ukrainians to look for other sources" from which to buy arms and ammunition, said the U.S. official, who said he has questioned senior White House and State Department officials about the issue. He said he received only a cryptic response from both that the sales are still being "evaluated," despite the Ukrainians already putting money down on them.

Two Ukrainian officials who spoke to BuzzFeed News believe the delays could be related to a Chinese attempt to buy a strategic Ukrainian aerospace company Motor Sich that the U.S. has tried to block, raising the possibility of Kyiv getting caught up in a power play between Beijing and Washington.

The Ukrainian and U.S. officials said the sales are vital to Ukraine's national security and would also strengthen Ukrainian President Volodymyr Zelensky's negotiating position as he pushes for lasting peace with Russian President Vladimir Putin. But the officials spoke on the condition of anonymity due to concerns about possible professional retaliation and because they weren't authorized to speak with the media about the matter.