WASHINGTON — Senate lawmakers said the deaths of four U.S. service members in unheralded anti-terrorism operations in Africa has brought new focus on the need to update the military force authorizations governing those missions.

But that hasn’t changed the debate.

At a Senate Foreign Relations Committee hearing on Monday, chamber leaders said they still don’t see a path forward for a new, bipartisan compromise on the issue, and administration officials testified that they don’t see a pressing need to repeal the 16-year-old authorizations under which U.S. troops are currently operating.

“The 2001 and 2002 authorizations to use military force remain a sound basis for ongoing U.S. military operations against a mutating threat,” Defense Secretary Jim Mattis said, adding that “any new congressional expression of unity” for U.S. troops would be welcome, if not necessary.

The testimony — the third hearing on the issue by the committee since the summer — repeats past comments from Mattis and other administration officials.

Former President Barack Obama had pushed to replace those open-ended authorizations before leaving office, and sent a draft of a more limited outline to Congress after U.S. military operations began against Islamic State group forces in the Middle East.

But Republicans called his proposals too limiting for future presidents, and some Democrats labeled them still too open-ended.

Since then, the issue has become a frequent topic of conversation on Capitol Hill without any significant legislative process. Sen. Jeff Flake, R-Ariz., noted that no current members of the foreign relations committee were in the Senate when the original authorizations were passed.

“We should have a chance to weigh in on this,” he said. “We ought to aspire to be more than part of a feedback loop.”

Committee chairman Sen. Bob Corker, R-Tenn., said he plans on holding more hearings on the issue in months to come, but admitted he sees little hope for progress on the issue.

“Moving ahead without significant bipartisan support would be a mistake in my opinion,” he said. “And right now, we are unable to bridge that gap.”

That leaves U.S. troops stationed in 19 foreign combat zones— including Iraq, Afghanistan, Syria and Niger — operating under the 2001 and 2002 authorizations.

Mattis and Secretary of State Rex Tillerson both testified that if lawmakers do adopt new military force authorizations, they must not include geographic limits or time constraints, given the constant evolving nature of the threat of foreign terrorists.

“We must recognize that we are in an era of frequent skirmishing, and we are more likely to end this fight sooner If we don’t tell our adversary the day we intend to stop fighting,” Mattis said.

Both Cabinet officials predicted that as coalition forces defeat ISIS fighters in the Middle East, those terrorist sympathizers are likely to expand to other areas of the globe. That means more military operations in more countries, and the possibility of more incidents like the ambush of U.S. troops in Niger earlier this month.

Last week, Senate Armed Services Committee Chairman John McCain, R-Ariz., said he is working with Democratic members on crafting another attempt at a bipartisan AUMF compromise, and expects to unveil the results in the near future.

He hopes to bring that idea before Corker’s committee, with more success than the other efforts so far.