(NBC NEWS) -- In a major address Thursday President Barack Obama sought to reframe the nation's counterterrorism strategy, saying, "Our systematic effort to dismantle terrorist organizations must continue. But this war, like all wars, must end. That's what history advises. That's what our democracy demands."
He said in a speech at the National Defense University in Washington, "America is at a crossroads. We must define our effort not as a boundless 'global war on terror' - but rather as a series of persistent, targeted efforts to dismantle specific networks of violent extremists that threaten America."
In an attempt to define a new post-Sept. 11 era, Obama outlined new guidelines for the use of drones to kill terrorists overseas and pledged a renewed effort to close the military detention center in Guantanamo Bay. In the speech, Obama argued that, "In the years to come, not every collection of thugs that labels themselves al Qaida will pose a credible threat to the United States." He warned that "unless we discipline our thinking and our actions, we may be drawn into more wars we don't need to fight."
With efforts under way in Congress to redefine the 2001 authorization to use military force (AUMF) against al Qaida, Obama said he would work with Congress "in efforts to refine, and ultimately repeal, the AUMF's mandate. And I will not sign laws designed to expand this mandate further."
Toward the end of Obama's address as he discussed the Guantanamo detainees, he was repeatedly interrupted by heckling from Medea Benjamin, founder of the antiwar group Code Pink, whose members have frequently been arrested for disrupting hearings on Capitol Hill - but Obama patiently said that Benjamin's concerns are "something to be passionate about."
"We must define the nature and scope of this struggle, or else it will define us, mindful of James Madison's warning that 'No nation could preserve its freedom in the midst of continual warfare.' Neither I, nor any president, can promise the total defeat of terror," he declared.
As part of his redefinition of counterterrorism, the president announced several initiatives:
Setting narrower parameters for the use of remotely piloted aircraft, or drones, to kill terrorists overseas and to limit collateral casualties;
Renewing efforts to persuade Congress to agree to close the Guantanamo detention site in Cuba where 110 terrorist suspects are being held;
Appointing a new envoy at the State Department and an official at the Defense Department who will attempt to negotiate transfers of Guantanamo detainees to other countries.
Lifting the moratorium he imposed in 2010 on transferring some detainees at Guantanamo to Yemen. Obama imposed that moratorium after it was revealed that Detroit "underwear bomber" Umar Farouq Abdulmuttalab was trained in Yemen.
Obama argued that when compared to the Sept. 11, 2001 attackers, "the threat today is more diffuse, with Al Qaida's affiliates in the Arabian Peninsula - AQAP - the most active in plotting against our homeland. While none of AQAP's efforts approach the scale of 9/11 they have continued to plot acts of terror, like the attempt to blow up an airplane on Christmas Day in 2009."
So he said, "As we shape our response, we have to recognize that the scale of this threat closely resembles the types of attacks we faced before 9/11."
He said that the current threat is often from "deranged or alienated individuals - often U.S. citizens or legal residents - (who) can do enormous damage, particularly when inspired by larger notions of violent jihad. That pull towards extremism appears to have led to the shooting at Fort Hood, and the bombing of the Boston Marathon."
In discussing his drone strategy he indicated his remorse over the innocent people who had been killed: "it is a hard fact that U.S. strikes have resulted in civilian casualties, a risk that exists in all wars. For the families of those civilians, no words or legal construct can justify their loss. For me, and those in my chain of command, these deaths will haunt us as long as we live, just as we are haunted by the civilian casualties that have occurred through conventional fighting in Afghanistan and Iraq."
There remains considerable doubt about Obama's ability to persuade a majority in Congress to change the current law on releasing detainees held there.
The defense spending bill which Obama signed into law last year prohibits any transfers to the United States of any detainee at Guantanamo who was held there on or before Jan. 20, 2009, the day Obama became president.
And the law sets a very high legal bar for Defense Secretary Chuck Hagel to transfer a detainee to his country of origin or to any other foreign country.
Hagel would need to certify to Congress that the detainee will not be transferred to a country that is a designated state sponsor of terrorism. The country must have agreed to take steps to ensure that the detainee cannot take action to threaten the United States, U.S. citizens, or its allies in the future.
The law allows Hagel to use waivers in some cases to transfer detainees.
In a mostly skeptical and sometimes dismissive reaction to Obama's speech, key Republican senators said at a press conference that he still had not offered a coherent plan for what to do with the different types of detainees held at Guantanamo, some of whom they said need to be held indefinitely, while others might be eligible for release.
Obama's 2008 opponent, Sen. John McCain, R- Ariz., said that "to somehow argue that al Qaida is 'on the run' comes from a degree of unreality that to me is really incredible." He argued that al Qaida is "expanding all over the Middle East" and in North Africa. He said repealing the congressional authorization to use military force "contradicts the reality of the facts on the ground."
Sen. Saxby Chambliss, R- Ga., the vice chairman of the Senate Intelligence Committee, noted that 56 of the Guantanamo detainees are Yemenis and that since 2010 the Yemeni government has "absolutely not" shown any indication that it can prevent released detainees from planning and carrying out terrorist attacks on Americans. "If we were to transfer those individuals to Yemen, it would be just like turning them loose," Chambliss told reporters.
Sen. Lindsay Graham, R- S.C. said "I believe we're in a war that's not winding down; we're in a war that's morphing. And the theme of the speech was that this war is winding down.... the justification for closing Gitmo is that we've destroyed the al Qaida leadership" but "that is not true."
Speaking a day before Obama's speech, Ben Wittes, senior fellow at the Brookings Institution and co-founder of the Lawfare blog which covers detainee news, said, "I don't see any significant change in congressional sentiment right now" on closing the Guantanamo site.
Obama has "got a lot of domestic pressure from his base to be seen to be doing something and he's also got a hunger strike there (at Guantanamo) - and I think there's a lot of genuine sentiment in the administration that they want to do something (about Guantanamo) so they're committed to another push and trying again - but the question of what they actually could get done is a difficult question. There's very limited latitude."
By Tom Curry, National Affairs Writer, NBC News