Defense Department positions since Trump's first term in office in 2017 and, more recently, was responsible for coordinating U.S. aid for Ukraine during the full-scale war that broke out in 2022.Politico linked her resignation to the growing uncertainty about upcoming changes in the Pentagon under Trump's administration, namely regarding the future Ukraine policy.According to the outlet, Cooper's resignation may also be connected to her testimonies in Trump's impeachment inquiry in 2019. The proceedings were launched after the then-U.S. president was said to pressure Ukraine to investigate his political rivals by threatening to withhold military aid.Often critical of the Biden administration's extensive backing of Kyiv, Trump has pledged to bring a swift end to the full-scale war by pushing Ukraine and Russia to the negotiating table.The incoming U.S.