President Donald Trump’s nominee to be the military’s top weapons buyer was the official who directed the Pentagon to withhold aid from Ukraine in 2019.

Jack Taylor/Getty Images(CNN) - House Democratic impeachment investigators have issued subpoenas to three Trump administration officials whose testimony was previously scheduled, in a sign the Democrats are trying to compel testimony from Trump officials who are apparently reluctant to appear. The subpoenas call for Duffey to appear on November 5 and Vought and Brechbuhl to testify on November 6. The committees leading the Democratic impeachment inquiry Intelligence, Foreign Affairs and Oversight have issued subpoenas to current State Department and Pentagon officials the morning of their testimony, in an effort to combat the Trump administration directing officials not to participate. It's not clear whether the subpoenas will prompt any of the three officials to participate. Both OMB and the State Department in addition to other federal agencies and the White House have already failed to comply with House subpoenas from the impeachment inquiry for documents.

Bob Kovach/CNN(CNN) - The House's impeachment inquiry is in full swing, and when lawmakers return this week, they've got several high-profile individuals from across the State Department, Pentagon and Office of Management and Budget whom they plan to interview in closed-door depositions. A list of depositions scheduled for this week provided by two congressional sources contained four names of individuals scheduled to testify. ThursdayDeputy Assistant Secretary of Defense Laura CooperCooper's purview as deputy assistant secretary includes Russia, Ukraine and Eurasia. State Department official Suriya JayantiJayanti, a State Department official and career foreign service officer, was stationed in the Ukrainian capital of Kiev. Tim Morrison, the National Security Council's senior director for Europe and RussiaMorrison replaced Fiona Hill on the National Security Council following her departure from the Trump administration over the summer.

Michael Duffey, OMB's associate director for national security programs and a Trump political appointee, signed at least some of the documents delaying aid to Ukraine, two sources told CNN. If directed to freeze aid to Ukraine, OMB staffers may have been concerned they were running afoul of the law by not spending the money as appropriated. At a staff briefing in mid-September, State Department officials confirmed that they no objection to the Ukraine funding going forward. The circumstances surrounding the Ukraine funding were also bizarre because the Trump administration provided such a wide variety of reasons to explain the delay. The one explanation the Trump administration rejects: That Trump may have halted money to Ukraine to pressure Ukrainian officials to investigate the Biden family.