WASHINGTON - A year after the U.S. raid that killed Osama bin Laden, al-Qaeda is hobbled and hunted, too busy surviving for the moment to carry out another Sept. 11-style attack on U.S. soil.

But the terrorist network dreams still of payback, and U.S. counterterrorist officials warn that, in time, its offshoots may deliver.

A decade of wars in Iraq and Afghanistan that have cost the United States about $1.28 trillion and 6,300 U.S. troops' lives has forced al-Qaeda's affiliates to regroup, from Yemen to Iraq. Bin Laden's No. 2, Ayman al-Zawahiri, is thought to be hiding, out of U.S. reach, in Pakistan's mountains, just as bin Laden was for so many years.

"It's wishful thinking to say al-Qaeda is on the brink of defeat," says Seth Jones, a Rand analyst and adviser to U.S. special-operations forces. "They have increased global presence, the number of attacks by affiliates has risen, and in some places like Yemen, they've expanded control of territory."

It's a complicated, somewhat murky picture for Americans to grasp.

U.S. officials say bin Laden's old team is all but dismantled. But they say new branches are hitting Western targets and U.S. allies overseas, and still aspire to match their parent organization's milestone of Sept. 11, 2001.

The deadliest is in Yemen.

"They are continuing to try to again carry out an attack against U.S. persons inside of Yemen, as well as against the homeland," White House counterterrorism adviser John Brennan said Sunday on ABC's This Week.

"We're working very closely with our Yemeni partners to track down all these leads," he said.

Brennan says there's no sign of an active revenge plot against U.S. targets, but U.S. citizens in Pakistan and beyond are being warned to be vigilant ahead of the May 2 anniversary of the night raid. U.S. helicopters swooped down on bin Laden's compound in the Pakistani army town of Abbottabad, killing him, one of his sons, two couriers, and their wives.

The last view for Americans of the mastermind behind the Sept. 11 attacks was that of a wizened old man sitting in front of an old television, wrapped in a blanket.

The world may never see photographic proof of his death. U.S. District Judge James E. Boasberg in Washington ruled last week that the Obama administration, under the Freedom of Information Act, would not have to turn over images of bin Laden during or after the raid.

"Verbal descriptions of the death and burial of Osama bin Laden will have to suffice," Boasberg wrote in his ruling on the lawsuit by the public-interest group Judicial Watch.

Bin Laden's killing and al-Qaeda's stumbling efforts to regroup are now the national security centerpiece of President Obama's reelection campaign.

The White House frequently cites the president's decision to approve the raid with only a 50-50 chance that bin Laden was at the compound. Obama could have gone down in history as the man who put Navy SEALs and the relationship with Pakistan in jeopardy, while failing to catch the al-Qaeda leader.

"Al-Qaeda was and is our No. 1 enemy," White House spokesman Jay Carney said last week. "So it's a part of his foreign-policy record, obviously, but it's also part of a very serious endeavor to keep our country safe."

How safe remains in question.

U.S. officials say al-Qaeda is less able to carry out a complex attack like Sept. 11, and they rule out al-Qaeda's ability to attack with weapons of mass destruction in the coming year. These officials spoke on condition of anonymity because they say that publicly identifying themselves could make them a target of the terrorist group.

U.S. counterterrorist forces have killed roughly half of al-Qaeda's top 20 leaders since the raid. That includes U.S.-born cleric Anwar al-Awlaki, killed by a drone in Yemen in September, less than six months after bin Laden's death.

Only a few of the original al-Qaeda team members remain, and most of the new names on the U.S. target lists are relative unknowns, officials say.

"The last terror attack was seven years ago in London, and they haven't had any major attacks in the U.S.," says Peter Bergen, an al-Qaeda expert who once met bin Laden. "They are recruiting no-hopers and dead-enders."

Yet Zawahiri is still out there. Though constantly hunted, he has managed to release 13 audio and video messages to followers since bin Laden's death, a near-record rate of release, according to the IntelCenter, a private intelligence firm. He has urged followers to seize on the unrest left by the Arab Spring to build organizations and influence in Egypt, Libya, and elsewhere, and back rebels in Syria - a call that U.S. intelligence officials say is being heeded.

U.S. attempts to deliver a "knockout punch" to Zawahiri and his followers in Pakistan have been hamstrung by a breakdown in relations with Pakistan's government over the bin Laden raid.

Pakistani officials saw the raid as a violation of their sovereignty, made worse by a U.S. friendly-fire attack that killed almost two dozen Pakistani troops on the border with Afghanistan last fall. Pakistan's parliament called for a redrafting of what the United States is allowed to do, and where.

CIA drone strikes in Pakistan's border area continue, but are limited to a relatively small area of the tribal region.