Under Mick Mulvaney’s leadership, the Office of Management and Budget temporarily put a hold on the delivery of anti-tank missiles to Ukraine in 2017 because of concerns their arrival would upset Russia, according to former White House official Catherine Croft.

She described OMB’s objection as “highly unusual.”

Croft’s testimony indicates that concerns about the U.S. relationship with Russia had a direct—though short-lived—impact on U.S./Ukraine policy in the first year of Trump’s presidency.

Croft told congressional impeachment investigators that after the Trump administration greenlit the delivery of Javelin missiles to Ukraine in late 2017—the first delivery of lethal aid to the country since Russian separatists seized territory in its Eastern region in 2014—Mulvaney’s office held it up.

“Did you understand why?” asked the congressional staffer questioning her.

“I understood the reason to be a policy one,” she replied.

“What was the policy one?”

“In a briefing with Mick Mulvaney, the question centered around the Russian reaction,” she continued.

“What was the concern about the Russian reaction?” asked the staffer.

“That Russia would react negatively to the provision of Javelins to Ukraine,” she said.

The Daily Beast first reported last month that OMB held up the 2017 shipment of Javelins to Ukraine. Croft said the hold lasted “about a week or two,” and that “all of the policy agencies” wanted the aid to go to Ukraine. She said OMB’s interest in the decision about whether to send Javelins to Ukraine was abnormal.

“[It] was rather unusual to have OMB expressing concerns that were purely policy-based and not budget-oriented,” she said.

“At the beginning of the Ukrainian Javelin process, I had been told that OMB was taking a policy interest,” she continued. “And OMB began sending working level officials to attend meetings... which was very unusual at the time.”

She noted that OMB staff also started attending meetings regarding aid to countries besides Ukraine and that the increase in their involvement was “quite taxing on a very small organization.”

Mulvaney and several other OMB officials have refused to participate in the congressional impeachment inquiry.