The Pentagon said Tuesday that its work to comply with the six congressional investigations into the September 2012 attack in Benghazi, Libya, has cost the military millions of dollars and thousands of man hours.

The Pentagon said in a letter to Rep. Adam Smith David (Adam) Adam SmithWhen 'Buy American' and common sense collide Overnight Defense: Marine Corps brushes off criticism of Marines' appearance in GOP convention video | US troops injured in collision with Russian vehicle in Syria | Dems ask for probe of Vindman retaliation allegations Democrats press Pentagon watchdog to probe allegations of retaliation against Vindman brothers MORE (Wash.), the top Democrat on the House Armed services Committee, that Defense Department officials have participated in 50 congressional hearings, briefings and interviews about the attack.

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“We continue to work fervently to address outstanding items which include a document request from the chairman of the Armed Services Committee (HASC) and six additional interviews of military personnel by HASC and House Oversight and Government Reform Committee staff,” wrote Elizabeth King, assistant secretary for legislative affairs.

Smith requested the estimate from the Pentagon in December. In response, he blasted the Armed Services Committee for continuing to investigate the terrorist attack on the U.S. compound in Benghazi, which killed Ambassador Chris Stevens and three other Americans.

Smith wrote to House Armed Services Chairman Buck McKeon Howard (Buck) Philip McKeonBottom Line Trump pick brings scrutiny to 'revolving door' between Pentagon, industry Bottom line MORE (R-Calif.), calling on him to drop the committee’s investigation.

“We must stop wasting this committee’s and our military’s scarce resources chasing a scandal that does not exist,” Smith wrote in a letter obtained by The Hill.

“More than any other committee in Congress, this committee should understand the financial strain on the Department of Defense, which is being made worse by these ongoing and ridiculous investigations,” Smith said.

It does not appear that McKeon intends to abandon the investigation, however.

“It is important that the committee see this oversight effort through to its conclusion,” said McKeon spokesman Claude Chafin.

“Chairman McKeon appreciates Ranking Member Smith’s concerns as well as the support he has given to our oversight of this matter,” he said. "The chairman also appreciates the support the Committee has received from the Department of Defense as we seek a full understanding of these tragic events.”

The Armed Services Committee has launched an investigation that largely cleared the Pentagon of failing to respond to the attack. While the committee’s investigation questioned the military’s force posture in the run-up to Sept. 11, 2012, the committee has also de-bunked accusations that the military was given a “stand-down” order.

In his letter to McKeon, Smith said that the Armed Services panel’s cooperation with the House Oversight Committee has “lent weight to some of the ridiculous accusations against our military leaders by some members” of the Oversight panel.

Republicans have contended that the Obama administration is still not being transparent about the Benghazi, while Democrats have accused the GOP members of engaging in a partisan witch-hunt.