Washington — Defense Secretary Mark Esper said the Pentagon is planning to comply with oversight requests made by congressional committees leading the impeachment inquiry, including a subpoena for documents about a delay of hundreds of millions of dollars in military assistance to Ukraine over the summer.

"We will do everything we can to cooperate with the Congress," Esper said on "Face the Nation" Sunday. "Just in the last week or two, my general counsel sent out a note — as we typically do in these situations — to ensure documents are retained."

Asked to confirm that his department intends to comply with the specific subpoena for documents related to the $250 million military aid package to the Ukrainian government, Esper responded in the affirmative.

"That's a yes," he said. "We will do everything we can to comply."

Last week, the House Intelligence Committee, one of three panels spearheading the impeachment inquiry, issued a subpoena addressed to Esper asking for Pentagon documents that Democratic investigators hope will shed some light into the sequence of events that led to the delay in providing the congressionally-approved military funds to Ukraine.

The White House counsel wrote in a letter last week that no member of the executive branch would cooperate with the impeachment inquiry.

Last year, Congress authorized the Department of Defense to dispatch the multi-million military aid package to Ukraine to bolster the government's efforts to counter the Russian-backed insurgency in the country's eastern territories. On June 28 of this year, the Pentagon said it was ready to provide the funds.

The aid, however, was mysteriously withheld by the White House for months, prompting Republicans and Democrats alike to publicly and privately express their concerns over the delay. Amid the mounting bipartisan pressure, the White House finally lifted its hold over the funds on September 11.

But the release of a White House memorandum of a July call between Mr. Trump and Ukrainian President Volodymyr Zelensky later in September prompted House Democrats to launch the impeachment inquiry, in part to probe whether the president used the military aid as leverage in his efforts to pressure the Ukrainian leader to investigate former Vice President Joe Biden and his son, Hunter.

In its subpoena, the House Intelligence Committee asked Esper to turn over the documents by this Tuesday.