President Trump, flanked by Secretary of State Rex Tillerson and Secretary of Defense Jim Mattis speaks during a Cabinet meeting in the White House on Monday. (Jabin Botsford/The Washington Post)

The Senate Foreign Relations Committee is taking up a long-awaited debate about authorizing military force against the Islamic State as President Trump comes under unprecedented public scrutiny for his treatment of dead soldiers' families, following an ambush on troops helping to fight Islamic terrorists there.

Senators will grill Secretary of State Rex Tillerson and Defense Secretary Jim Mattis in an open hearing on Oct. 30 about whether the administration thinks it is necessary for Congress to pass a new authorization for use of military force, or AUMF, to replace existing AUMFs that date back to the early years of the George W. Bush administration. The hearing is seen as a precursor to a more congressionally driven legislative effort to write an AUMF that can draw enough Republican and Democratic support to pass.

Lawmakers have wrangled for years over whether or how to replace the existing 2001 AUMF, which authorized operations against al-Qaeda, the Taliban, and affiliated groups in the wake of the Sept. 11 attacks, and the 2002 AUMF, which allowed for operations in Iraq, with a new AUMF more focused on present-day and future threats — particularly the Islamic State. Many members of Congress have charged that the existing AUMFs do not provide a firm legal basis for current operations, a view that both the Obama and Trump administrations have argued against.

But the timing of this hearing has put an increased urgency behind the AUMF debate, as Congress and the nation demand answers about what led to the deaths of four U.S. Special Forces in Niger on a support mission to fight Islamic terrorists like the Islamic State.

"The many questions surrounding the death of American service members in Niger show the urgent need to have a public discussion about the current extent of our military operations around the world," said Sen. Tim Kaine (D-Va.), co-author with Sen. Jeff Flake (R-Ariz.) of the AUMF proposal that has gained the most momentum in Congress. "A new AUMF is not only legally necessary, it would also send an important message of resolve to the American public and our troops that we stand behind them in their mission."

Senate Foreign Relations Committee Chairman Bob Corker (R-Tenn.), who in recent weeks has scathingly criticized Trump's tenure as commander in chief, has been promising to restart the AUMF debate for months. The Niger attack has now mired the Trump administration in further controversy, as Capitol Hill's top hawks demand to know why they were largely left in the dark about the operation.

The Niger attack has also led to scrutiny about how Trump treats the families of fallen solders. It took 12 days for the president to place condolence calls to the soldier's families — something Trump defended by arguing that President Barack Obama never called Trump's current chief of staff, Gen. John Kelly, when his son died in Afghanistan. When Trump did place the phone calls, he made the widow of one of the service members cry by telling her that her husband, Sgt. La David Johnson, "must have known what he signed up for," according to Florida Democratic Rep. Frederica S. Wilson. Trump has vehemently denied the conversation, and Kelly defended Trump's actions to reporters Thursday, speaking about his own personal tragedy with his son, something he has long tried to keep separate from politics.