The US has held up at least six arms sales to Ukraine, and it's a mystery as to why, according to a new report from BuzzFeed News.

The report came one day after President Donald Trump was acquitted in an impeachment trial linked to his dealings with Ukraine, including freezing almost $400 million in military aid for several months last year.

Collectively, the arms sales reportedly amount to roughly $30 million.

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The US government has held up nearly $30 million in arms sales to Ukraine, in some cases for over a year, and the Ukrainian government wants its money back, according to a new report from BuzzFeed News.

It's a mystery as to why at least six sales of arms and ammunition have been held up, according to the report, which cites both several current Ukrainian officials and a former US official.

"It might be wise for the Ukrainians to look for other sources," the former US official told BuzzFeed's Christopher Miller.

When asked about the delay by Insider, a State Department spokesperson said, "The Department is restricted under the Arms Export Control Act and the International Traffic in Arms Regulations from commenting on the status of specific defense trade direct commercial licensing cases."

The White House did not immediately respond to a request for comment from Insider on why final approval has allegedly not been granted on these sales.

But the delay could be linked to the US attempting to block China from buying a Ukrainian aerospace company, according to the BuzzFeed report. Last summer, then-national security adviser John Bolton was concerned that the acquisition of this company would give Beijing access to important defense technology, the Wall Street Journal reported in August.

The BuzzFeed report came one day after President Donald Trump was acquitted on two articles of impeachment, which were linked to his effort to pressure Ukraine to launch inquires into his political rivals as he simultaneously froze almost $400 million in congressionally-approved security assistance to Kiev.

Democrats essentially accused Trump of soliciting foreign election interference and attempting to use military aid to blackmail Ukrainian President Volodymyr Zelensky into digging up dirt on former Vice President Joe Biden, a top contender for the 2020 Democratic nomination, as well as a debunked conspiracy theory on the 2016 election.

The security assistance was released in early September after being placed on hold for months — less than a week after three House committees launched investigations into Trump's dealings with Ukraine.

The Government Accountability Office (GAO), an independent government watchdog, in January said that the freeze on the aid was illegal. Specifically, the GAO said the Trump administration had violated the Impoundment Control Act.

Trump has maintained he did nothing wrong, declaring victory in an expletive-filled rant in the East Room of the White House on Thursday morning.

Ukraine is in the midst of an ongoing war with pro-Russian separatists that's estimated to have killed over 14,000 people and displaced roughly 1.5 million.

Throughout the impeachment proceedings, the president and his Republican allies touted his administration's sale of Javelin missiles to Ukraine as evidence he's supported it against Russian aggression. But based on the terms of the sale, Ukraine cannot actually use these weapons in the conflict in the eastern part of the country.

As Insider previously reported, the Trump administration first approved the sale of Javelins to Ukraine in December 2017. The sale was competed in March 2018, when the State Department announced it would sell Ukraine 210 Javelin anti-tank missiles and 37 launchers worth $47 million. The State Department approved an additional sale of the anti-tank missiles to Ukraine in October.

One of Trump's central defenses against impeachment was that Zelensky said he felt "no pressure" to launch investigations into the US president's political rivals. But impeachment witnesses, including former US ambassador to Ukraine Bill Taylor, said that Zelensky would never admit to feeling pressure due to Ukraine's culture and the fact Kiev is heavily reliant on US assistance amid an ongoing, bloody war.

Five of the six sales that are currently pending were placed on hold roughly a year ago, and one has been on hold for more than a year, according to BuzzFeed. This means the sales were delayed prior to Trump's July 25 phone call with Zelensky that was at the center of the impeachment proceedings.