U.S. air strikes in Syria have suddenly revived a debate in Congress about whether to take up a new measure to authorize the president to use military force.

Almost as soon as the strikes were announced, there were bipartisan calls for Congress to debate a new Authorization for Use of Military Force, or AUMF.

"The President needs congressional authorization for military action as required by the Constitution, and I call on him to come to Congress for a proper debate," Sen. Rand Paul, R-Ky., said in a statement. "Our prior interventions in this region have done nothing to make us safer, and Syria will be no different."

Sen. Tim Kaine, D-Va., accused Trump of breaking the law.

"Congress will work with the president, but his failure to seek congressional approval is unlawful," Kaine said.

Senate Armed Services Committee Chairman John McCain, R-Ariz., earlier Thursday said said Syrian air strikes should require a new AUMF, though he praised the strikes in a statement late Thursday that made no mention of a need for new authorization.

Shortly after the strikes were announced, Rep. Adam Schiff, D-Calif., the ranking member of the House Intelligence Committee, said he would introduce such a resolution when Congress returns from a two-week recess.

But so far, no GOP leader in either chamber has pledged to take up a new AUMF, which is typically one of the most politically difficult votes a lawmaker in either party can take.

"I commend our troops for their professionalism in carrying out these strikes. Assad has made his disregard for innocent human life and longstanding norms against chemical weapons use crystal clear," Senate Majority Leader Kevin McCarthy, R-Calif., who controls the floor schedule, said in a statement. "Tonight's strikes show these evil actions carry consequences,"

Congress has dodged taking up a new authorizing measure since passing a pair of authorizing resolutions more than 15 years ago.

The first AUMF, in 2001, gave President Bush permission to attack Afghanistan in the wake of the September 11 terrorist attacks. In 2002, Congress acted again to give Bush authorization for the use of military force, this time against Iraq.

Lawmakers have since then debated whether subsequent military action is covered under either 2001 or 2002 resolutions but have steered away from formally taking the debate to the House or Senate floor with new legislation.

President Obama operated under the AUMFs of 2001 and 2002 throughout his presidency, including the limited military intervention in the Middle East to combat ISIS, which has been comprised mostly of air strikes and some ground troops.

In 2013, Obama dropped a planned military strike against Syria in response to a chemical weapons attack. Instead, he sought authorization for the move from Congress.

But lawmakers refused to take up an AUMF.

Neither the Republican-led House nor the Democrat-run Senate would move to bring up a resolution, considered political poison after the 2006 elections that cost Republicans the House majority in part because of strong voter anti-war sentiment.

Lawmakers in both parties rejected a draft AUMF resolution sent by President Obama in February 2015 seeking permission to attack Islamic State militants.

Democrats thought it went too far in involving U.S. military in another overseas fight, while Republicans said the plan was too restrictive for the military to be able to effectively carry out the mission.

By late Thursday, there were steady calls for Trump to outline his strategy in Syria now that the U.S. has attacked.

"President Trump must follow them with the presentation of a clear and coherent strategy and the articulation of what discernible goals these strikes were meant to advance," House Minority Whip Steny Hoyer, D-Md., said.

Congress passed the first AUMF on Sept. 14, 2001. It authorized the president "to use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons."