Democratic lawmakers issued subpoenas to the Pentagon and the White House budget office on October 7 as part of their impeachment inquiry demanding documents related to President Donald Trump's move to withhold military assistance from Ukraine.
Democrats in the House of Representative have already issued subpoenas for the White House, Vice President Mike Pence, and the State Department, including Secretary of State Mike Pompeo.
The three House committees leading the probe said the documents must be turned over by October 15, warning that failure to comply may be seen as obstruction and held against any officials in the executive branch.
The Democrats said in a letter to U.S. Secretary of Defense Mark Esper that their investigation is focusing on whether Trump endangered national security by seeking foreign interference in the upcoming U.S. elections and withholding military aid to Ukraine.
The three committees -- House Intelligence, Oversight and Foreign Affairs Committees -- are investigating Trump in the impeachment probe related to a July 25 phone call with Ukrainian President Volodymyr Zelenskiy.
During the call, according to a government whistle-blower complaint, Trump had allegedly asked Zelenskiy for help in investigating Joe Biden, the former vice president and a promising presidential candidate for next year’s election, as well as his son, Hunter, for his involvement with a Ukrainian energy firm.
The complaint claimed that Trump was "using the power of his office to solicit interference from a foreign country" in the 2020 U.S. election.