U.S. Deputy Assistant Secretary of Defense Laura Cooper, who was in charge of Russia, Ukraine and Eurasia affairs, resigns, Politico reported on Tuesday.

"Cooper, who spent more than two decades at the Pentagon, is probably best known for testifying to Congress over the objections of department leadership as part of Trump's Ukraine-related impeachment trial. The Defense Department didn't say why Cooper left, but given her testimony and the uncertainty over Ukraine policy, the Pentagon might have proven an uncomfortable place for her under the new president," it said.

According to the publication, Cooper played an outsized role in coordinating the massive shipments of U.S. military aid to Ukraine since Russia first invaded in 2022. But Pentagon and State Department officials who worked closely with her said they feared she would have a target on her back under Trump for her testimony and ties to Biden-era Ukraine policy. We granted all of them anonymity to discuss the matter candidly.