Congress first passed an "Authorization for the Use of Military Force" or AUMF on September 14, 2001 -- three days after the devastating attacks on New York and Washington by Al-Qaeda hijackers.
![Ana Estrada suffered from polymyositis, an incurable disease that weakens muscles [Elias Alfageme/GDA via AP]](data:image/svg+xml;charset=utf8,%3Csvg%20xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg'%20width%3D'100'%20height%3D'100'%20data-ring-placeholder%3D'1'%3E%3C%2Fsvg%3E "Ana Estrada suffered from polymyositis, an incurable disease that weakens muscles [Elias Alfageme/GDA via AP]")
Since then, three presidents in succession have relied on the order's authority as they launched operations against armed Islamist groups in far-flung battle zones around the world.
Critics have long-contended that presidents George W. Bush, Barack Obama and now Donald Trump have exceeded the terms of an authorization initially aimed at Osama Bin Laden's Al-Qaeda organization.
Most recently, after four US soldiers were killed last week in an ambush by militants in Niger, many Americans were surprised to learn the Pentagon has deployed hundreds of troops in West Africa.
Some lawmakers are now pushing their colleagues to reassert Congress' right, under the constitution, to decide when and where the United States can go to war, in the face of some White House resistance.
Secretary of Defense Jim Mattis and Secretary of State Rex Tillerson are to testify before the Senate Foreign Relations Committee on the need or otherwise for a new or updated AUMF.
"As we face a wide array of threats abroad, it is perhaps more important than ever that we have a sober national conversation about Congress' constitutional role in authorizing the use of military force," said committee chairman Senator Bob Corker.
"We look forward to hearing from Secretary Tillerson and Secretary Mattis and appreciate their willingness to appear before our committee."
In August, both men testified behind closed doors on the same topic and afterwards the Republican chairman Corker said they'd been "open" to the idea of revisiting the issue.
Niger ambush
"The administration is not seeking" a new AUMF, Corker told reporters after the August hearing, but "they wouldn't be opposed to one that was written in the appropriate way."
Since then, however, Corker has fallen out with Trump and become an open critic of the president, and calls for new oversight on US operations in Africa, the Middle East and Asia have grown.
In September, anti-war Republican Senator Rand Paul attempted to pass an amendment to a funding bill that would have repealed the AUMF.
And, ahead of Monday's hearing, Democrat foreign relations committee member Senator Tim Kaine promised that Mattis and Tillerson would not get an easy ride in wake of the Niger deaths.
"After the deaths of service members in Niger this month, questions have risen about the extent of US military operations around the globe and the legal justification behind current military efforts," he said.
"At the hearing, Kaine will stress the need for a new AUMF to better define the US fight against terrorist organizations and to send a message to the troops, the American public, and US allies that Congress supports the military's mission."
Eyewitness? Submit your stories now via social or:
Email: eyewitness@pulse.ng
![The 10 warmest years have occurred since 2007 [Black Doctor]](data:image/svg+xml;charset=utf8,%3Csvg%20xmlns%3D'http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg'%20width%3D'300'%20height%3D'172'%20data-ring-placeholder%3D'1'%3E%3C%2Fsvg%3E "The 10 warmest years have occurred since 2007 [Black Doctor]")
