[1] McCusker was nominated by President Donald Trump to become United States Principal Deputy Under Secretary of Defense in April 2017 and was confirmed on August 1, 2017.

[10] McCusker was identified as one of the federal officials with knowledge of President Trump's effort to keep Ukraine from receiving aid authorized by Congress.

Emails that she sent and received regarding the matter were included in documents obtained by the Center for Public Integrity in response to a Freedom of Information Act request.

[11] Michael Duffey, a political appointee in White House's Office of Management and Budget (OMB), emailed McCusker and others an hour and a half after Trump's call with Ukrainian leader Zelenksy, requesting they "hold off" on distributing aid to Ukraine.

[12] McCusker then sent emails to the OMB expressing concern that by withholding funds from Ukraine, the White House was violating the Impoundment Control Act, which requires that the executive branch spend appropriations that have been approved by Congress.