WASHINGTON - President Obama said Thursday that the United States has reached a "crossroads" in the fight against terrorism and that it is time to redefine and recalibrate a war that will eventually end.

Far from repudiating the controversial use of drones against terrorist targets, Obama defended the tactic as effective, legal, and lifesaving. But he acknowledged that threat levels have fallen to levels not seen since before the 9/11 attacks, requiring new criteria for use of lethal force.

Obama used the first major counterterrorism address of his second term to outline newly narrowed guidelines to deploy drones only against targets that pose a "continuing, imminent threat" to the United States and only in cases where avoiding civilian casualties is a "near certainty."

"As our fight enters a new phase, America's legitimate claim of self-defense cannot be the end of the discussion," Obama said. "To say a military tactic is legal, or even effective, is not to say it is wise or moral in every instance."

In a lengthy, wide-ranging speech at the National Defense University at Fort McNair, Obama used the depiction of a diminished threat environment to make the case for sweeping changes to the counterterrorism landscape, including closing the prison at Guantanamo Bay, Cuba, and finding a U.S. site where military commission trials can be held for eligible detainees.

Among steps to help thin the detention center's population of 166 people, many of them now on a hunger strike, he called for an end to congressional restrictions on transfers for those cleared to leave, and said he was lifting his own moratorium on the repatriation of several dozen Yemeni prisoners.

But even while declaring that "this war, like all wars, must end," Obama made clear that other pieces of the counterterrorism apparatus will remain in place, including targeted killings with drones. He made no mention of ending the CIA's involvement in the drone campaign.

Obama's remarks followed a pledge in his State of the Union speech in January to make his counterterrorism policies - particularly about drones - more transparent and accountable to Congress and the American public.

Congressional responses ran the gamut. "The president's speech today will be viewed by terrorists as a victory," said Sen. Saxby Chambliss of Georgia, the ranking Republican on the Senate Intelligence Committee. "Rather than continuing successful counterterrorism activities, we are changing course with no clear operational benefit."

Rep. Adam Schiff (D., Calif.), a member of the House Intelligence Committee, said the speech went further in describing the president's vision of countering a diminished terrorist threat than it did in delineating how it will go about doing so.

"It seemed like the administration is using a two-tiered approach," Schiff said. "A public speech to set up a broad idea that we're at a crossroads. And at the same time a more private track which changes the criteria and adds restrictions to the drone program."

As a result, Schiff said, Obama "raised a number of questions as well as answering some."

Obama sought to both describe a reduced threat level and avoid dismissing the risk. "Now make no mistake," he said, "our nation is still threatened by terrorists. From Benghazi to Boston, we have been tragically reminded of that truth." But rather than "the threat that came to our shores on 9/11," he said al-Qaeda was now "on a path to defeat."

He outlined a threefold danger from weakened al-Qaeda affiliates, threats to diplomatic facilities and businesses abroad, and homegrown extremists.

"This is the future of terrorism," Obama 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."

Obama said he would not sign any proposed expansion of the 2001 Authorization for the Use of Military Force, which gives the president the power to use military force against al-Qaeda. Some lawmakers have argued that the authorization should be revised because it is now used to justify targeted killings against al-Qaeda "associates" in Yemen and Somalia, far removed from the 9/11 attacks. Obama said he would work to refine and ultimately repeal the mandate.

"America is at a crossroads," he said. "We must define the nature and scope of this struggle, or else it will define us."

Senior administration officials said some of the specifics of the changes Obama outlined are contained in a classified Presidential Policy Guidance directive on counterterrorism operations that he signed this week.

The officials, who spoke on condition of anonymity to brief reporters before the speech, said that requiring evidence of "a continuing and imminent threat to the United States" to justify a drone strike was more restrictive language than in the past.

The officials said the "near certainty" that civilians would not be hit tightens a previous standard in which civilians have been killed unintentionally. Obama said there was "wide gap" between the estimated thousands of civilian casualties cited by nongovernmental organizations and U.S. tallies.

Drone Policy at a Glance

President Obama defended the use of drone attacks as an important part of the U.S. counterterrorism policy on Thursday but signed new presidential policy guidelines to spell out for Congress and the public the standards that the United States will use before carrying out drone attacks.

The guidelines include not using strikes when the targeted people can be captured either by the United States or a foreign government, relying on drones only when the target poses an imminent threat, and establishing standards for notifying members of Congress.

A look at the new policy:

Preference for Capture

The policy is to refrain from using lethal force "when it is feasible to capture a terrorist suspect" because the capture of a potential terrorist offers the opportunity to gather intelligence and disrupt terrorist plots. Operations to capture a terrorist suspect can only be conducted against those who may lawfully be captured by the United States and "only when the operation can be conducted in accordance with applicable law."

Lethal force will only be used to prevent or stop attacks against Americans. There must be a legal basis for using lethal force, and the U.S. will

only use lethal force against a target that poses "a continuing, imminent threat to U.S. persons."

U.S Government Coordination and Review

The decisions to capture or use force against individual terrorist suspects outside the United States and areas of active hostilities are made at the most senior levels of the federal government. Senior national security officials will consider

proposals to ensure that the administration's policy standards are met, and attorneys will review and determine the legality of the proposals.

The decisions will be informed by a "broad analysis" of the target's role in plots threatening Americans, the intelligence information the individual could provide, and the potential impact on ongoing terrorism plotting.

American Targets

If the U.S. considers conducting an operation against a terrorist suspect who is identified as an American, the Justice Department will perform an additional legal analysis to ensure the action is consistent with the Constitution and the laws of the

United States.

Reservation of Authority

These new standards and procedures do not limit the president's authority to take action in extraordinary circumstances when doing so "is both lawful and necessary to protect the United States or its allies."

Congressional Notification

Appropriate members of Congress will be updated regularly on the identities of any individuals against whom lethal force has been approved. Appropriate committees will be notified whenever a counterterrorism operation covered by these standards and procedures has been conducted.

SOURCE: The White HouseEndText