Updated 6/7/20 at 4:30 PM EST with comments from Smith and Hoffman.

WASHINGTON — Capping of a tumultuous week of questions about civil-military affairs and the role of the U.S. military, Secretary of Defense Mark Esper and Gen. Mark Milley, chairman of the Joint Chiefs of Staff, have turned down a request to testify in front of the House Armed Services Committee.

A House aide confirmed on background that the two men have “refused” to testify next week, as was requested by HASC Chairman Rep. Adam Smith, D-Wash., requested Tuesday. In addition, an informal briefing planned for Friday with Secretary of the Army Ryan McCarthy was cancelled by the DoD.

In a Friday evening statement, Smith and 30 Democratic members of the HASC called the decision not to appear in front of the committee, which has oversight over the military, “unacceptable.”

“The House Armed Services Committee made the request and it has been denied. That is simply unacceptable. It is the constitutional duty of the House Armed Services Committee to perform rigorous oversight, just as it is the constitutional duty of the Administration to be accountable to the American people," the members wrote.

“Apparently, the Trump administration believes they have no obligation to explain their actions to Congress or respect our constitutional system of checks and balances,” Smith and the other continued, while noting that the informal briefing with McCarthy should be rescheduled immediately. "We look forward to receiving a briefing from the department no later than Monday, June 8, and receiving public, on-the-record testimony from Secretary Esper and General Milley shortly thereafter.”

Following Smith’s statement, a spokesman for HASC ranking member Rep. Mac Thornberry, R-Texas, took a more measured tone, saying that "it is important that the committee hear from the department to understand how those missions are affecting DoD’s resources and priorities. The timing of that exchange and the witnesses or briefers must, as always, be coordinated with the department.”

The Pentagon declined to comment on Friday, but over 24 hours after Smith’s statement was released, chief Pentagon spokesman Jonathan Rath Hoffman issued a comment denying that the department “refused” to attend the HASC meeting.

“The DoD legislative affairs team remains in discussion with the HASC on this request,” Hoffman said. "In the meantime, DoD has committed to provide Army Secretary McCarthy, Army Chief of Staff Gen. [James] McConville, and DC National Guard Commanding General Maj. Gen. [William] Walker to brief the committee next week on the presence of the National Guard in Washington, D.C., this past week.”

Spurning Smith’s request may lead to complications down the road for the Pentagon’s budget request, with Democrats in Congress already gearing up to use the annual National Defense Authorization Act to put restraints on how the military can operate on civil territory. It also adds fuel to questions about the proper civil-military relationship and how the American military can and should be deployed on domestic soil.

“This is a terrible time for the leadership of DoD to look like they’re trying to evade accountability,” said Kori Schake, a former national security official in the George W. Bush administration who now heads the defense practice at the American Enterprise Institute.

“Both committed during their confirmation hearings they would appear when Congress called. They should be using every opportunity to explain their choices — and also to explain things many Americans don’t know, like the different roles the National Guard has from active duty troops,” Schake said. “The House should refuse to hold an NDAA vote until they do.”

The news was first reported by Politico.

Lawmakers have been critical that Esper and Milley were among aides who accompanied Trump just after peaceful demonstrators were gassed in front of the White House Monday night. After the protesters were cleared, Trump posed for a photograph with a Bible in front of nearby St. John’s Episcopal Church, which was damaged by fire amid protests the night before.

Later that night, Esper and Milley, joined by Army Chief of Staff Gen. James McConville and Army Secretary Ryan McCarthy, visited National Guard troops in D.C.

A low-flying U.S. Army Lakota helicopter was also deployed to disperse protesters in the unrest in Washington, D.C., which followed the killing of George Floyd, a Minnesota man who was being arrested by police. During a White House call with state governors earlier in the day, Esper urged them to let National Guard forces “mass and dominate the battlespace” to dissipate the unrest.

In a Wednesday press conference — one that led to a conflict with the White House and has raised questions about Esper’s job security — the secretary announced an investigation into the use of the helicopter, apologized for the use of the term “battlespace” to describe American territory, and said he was against the idea of using active duty military forces against civilians.

Both Esper and Milley have come under direct or indirect rhetorical fire from former defense officials for their participation in the Monday event. Among those weighing in this week on civil-military affairs and the current Pentagon leadership are former secretaries of defense Jim Mattis, Ash Carter and William Perry, and former chairmen of the joint chiefs of staff Martin Dempsey, Mike Mullen and Richard Myers.