Story highlights At least 65 militants killed since Saturday, Yemeni officials say

High-value targets believed killed in ground attack, Yemeni official says

A U.S. drone attack is suspected, but the official won't confirm it

Other officials express frustration and suspicion at the lack of details

A "massive and unprecedented" assault against al Qaeda fighters in Yemen appears to be targeting high-level operatives of the terrorist network, U.S. analysts said Monday.

It wasn't clear who those targets are, but Yemen's government says it has killed dozens of members of al Qaeda in the Arabian Peninsula in a joint operation with the United States. The ongoing push included a Sunday night ambush in which Yemeni special forces killed men believed to be top leaders of the group, a high-level Yemeni government official being briefed on the strikes told CNN on Monday.

The Yemenis collected the bodies and will perform DNA testing to determine the militants' identities, the official said. In addition, suspected U.S. drone strikes over the weekend pounded a mountain camp where al Qaeda fighters were training for attacks "against Yemeni and foreign interests," Yemen's Supreme Security Committee said.

U.S. authorities blame the Yemen-based branch of al Qaeda for a string of plots against Americans, including the failed attempt to blow up a U.S.-bound jetliner with a bomb concealed in an operative's underwear in 2009. CNN National Security Analyst Fran Townsend said the intensity of the strikes suggests there's a "very real" hope of capturing or killing a top al Qaeda figure.

"The fact that this is an ongoing effort with such massive resources behind it tells you that the target is a very high-value target," Townsend said. "You don't commit the Yemeni army, you don't commit the drones without the target being very real."

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By Monday night, at least 65 militants have been killed, some of them from neighboring Saudi Arabia, Yemeni officials said. Another three civilians were killed in a Saturday night drone strike, the high-level Yemeni official said earlier.

'Massive and unprecedented'

The official called the raids "massive and unprecedented." One of the sites targeted is in the same area where scores of al Qaeda followers had gathered recently to hear from Nasir al-Wuhayshi, the head of the terrorist network's Yemeni branch and the global organization's "crown prince," the official said.

In addition to the "undiebomber" plot on Christmas Day 2009, U.S. officials have said AQAP was behind a 2010 plan to load bombs onto cargo planes disguised as computer printers, another plot to blow up a jetliner in 2012 and a 2013 scheme to attack oil and gas ports in Yemen. Its chief bomb designer, Ibrahim al-Asiri, is believed to have dispatched his own brother in a 2009 attempt to kill Saudi Arabia's counterterrorism chief.

Al-Asiri is one of the main reasons AQAP has become "a direct threat" to the United States, Townsend said. Speculation swirled Monday that he was among the targets of the weekend's attacks, but Yemeni officials have so far identified only three men they said were midlevel leaders of the group.

Previous U.S. strikes have killed radical Yemeni-American cleric Anwar al-Awlaki and Fahd al Quso , an al Qaeda operative wanted in the bombing of the destroyer USS Cole in 2000.

The high-level Yemeni government official would not confirm whether drones were used in the weekend attacks, but the United States is the only country known to have conducted drone strikes in Yemen. As a rule, U.S. officials don't comment on those strikes, and Washington had little to say about the operation Monday.

"We support the Yemeni government's efforts to tackle terrorism within their own borders," White House spokesman Jay Carney told reporters. "And beyond that, for details of these reported incidents, I would refer you to the Yemeni government."

Growing frustration in Yemen

The high-level Yemeni official said it would take time to clarify the details of Sunday's strikes: whether the raids targeted camps, vehicles on the move or both, the full death toll among the militants and whether there were any civilian casualties.

But other Yemeni officials, who asked to remain anonymous as they are not authorized to speak to the media, said there was growing frustration within the government about the lack of clarity and expressed concern that some of the information the military is reporting may be propaganda.

"I'm worried this is an attempt to convince Yemenis that the U.S. and Yemen have turned a corner and are in the process of destroying AQAP," one of those other officials said. "At this hour, the numbers of militants being reported as being killed keeps changing, and we still aren't sure if any civilians have been killed or wounded in these strikes."

He added, "Yemenis are smart enough to doubt initial reports of this type. If this does turn out to be exaggeration, it will make the people here trust their government even less than they do and fuel growing anger over the drone program."

The United States first used armed drones to pick off an al Qaeda operative in Yemen in 2002. Strikes on suspected al Qaeda figures resumed in 2009, with more than 92 drone attacks since then, as well as a further 15 U.S. strikes using other forms of weaponry such as cruise missiles, according to a count by the New America Foundation , a U.S.-based think tank that tracks the raids.