08/02/2017 13:38 EDT | Updated 08/04/2017 13:44 EDT

Trump administration says current war authority sufficient

WASHINGTON — The Trump administration told Congress on Wednesday it has sufficient legal authority for military force against the Islamic State in Iraq and Syria based on the 2001 law to counter al-Qaida.

In a letter, the administration said the authorization for the use of military force that Congress passed after the Sept. 11 terror attacks grants the military the authority to defend U.S. and allied forces fighting against Islamic State militants. The administration said the authority extends to the fight against al-Qaida and associated forces, including the Islamic State of Iraq and Syria.

"This legal authority includes the 2001 Authorization for the Use Military Forces which authorizes the use of military force against these groups," the administration said. "Accordingly, the administration is not seeking revisions to the 2001 AUMF or additional authorization to use force."

The letter came Wednesday, the same day Secretary of State Rex Tillerson and Defence Secretary Jim Mattis were briefing members of the Senate Foreign Relations Committee on Capitol Hill.

Republicans and Democrats have raised questions about whether the 2001 law, passed as the U.S. was targeting al-Qaida, should be revised.

The letter to Congress reflected the administration's effort to affirm it's on solid legal footing as long as it is fighting IS extremists in the Mideast, even as the administration prepares for a post-IS situation in which the extremists are mostly vanquished and the focus turns to the longer term.

The Obama administration, too, argued that the law passed after Sept. 11 to fight al-Qaeda applied to the current effort in Iraq and Syria, because the 2001 law said the U.S. could go after al-Qaida affiliates. These days, al-Qaida's offshoot in Syria is distinct from IS — and in fact has been fighting IS. But both the Obama and Trump administrations have argued they're similar enough to both be fair game under the post-9-11 law.

But that argument, which critics have said for years stretches the post-9-11 law too far, becomes even less credible once IS is largely eliminated and the primary U.S. focus in Syria and Iraq moves beyond Trump's goal of defeating the group. The liberation of Mosul, the group's last urban stronghold in Iraq, and the impending fall of Raqqa, the de facto capital, have been seen as powerful indicators that the group may be nearing defeat.

Anticipating the defeat of IS, the administration is discussing with Congress the potential need for a post-IS war powers law to authorize U.S. activities to stabilize Syria and keep other extremist groups or Iran-backed militias from filling the vacuum of power. If the U.S. decided to issue a new authorization, for example, it could potentially facilitate temporarily sending in more troops to help restore order and normalcy on the ground, said a senior U.S. official, who wasn't authorized to discuss the deliberations publicly and requested anonymity.

Tillerson, speaking to reporters this week, argued the U.S. didn't plan to pull out abruptly and completely once IS is defeated, but also had no plans to embark on the kind of nation-building in the Middle East for which President George W. Bush's administration was criticized. Tillerson said in areas liberated from IS, the U.S. has sought to move in quickly to restore "fundamental needs" that allow residents to move back to their homes: electricity, water and sewage.

"That's where we stop," Tillerson said. "We get the essentials in place. We're not there to rebuild their communities. That's for them to do and that's for the international community to marshal the resources to allow them to do that."