Updated

What appeared to be the deadliest U.S. missile attack ever on Pakistani soil brought an unusual reaction in a country that has previously denounced such strikes as an affront to its sovereignty — silence.

Tuesday's attack killed 80 people, Pakistani officials said, but missed its chief target, Baitullah Mehsud. He is the country's top Taliban leader and its public enemy No. 1, accused of masterminding numerous brutal operations including the assassination of Benazir Bhutto.

The seemingly accurate targeting appeared to point to cooperation between the U.S. military and Pakistani intelligence — despite Pakistani denials. This was possible because Mehsud — unlike some other U.S. foes in the northwest tribal region on the Afghan border — is so reviled in Pakistan.

Missiles apparently fired by unmanned aircraft first struck a purported Taliban training center in South Waziristan, then another barrage rained down on a funeral procession for some of those who had been killed earlier.

Mehsud attended the funeral in Makeen village, and panicky militants reported losing contact with the Taliban chief for a short time immediately after the attack, according to radio intercepts cited by two Pakistani intelligence officials.

But the officials said they were later able to determine that Mehsud left the funeral shortly before the missiles struck.

The two missile strikes killed at least 80 people, including several senior militants, said the officials, speaking to The Associated Press on condition of anonymity because they were not authorized to divulge the information. Fifty-five of those killed were at the funeral, they said.

The Taliban gave a slightly lower count: Waliur Rehman, an aide to Mehsud, told the AP that 65 people were killed, including some militants.

It was not known if innocent civilians were among the dead, an issue that has drawn outrage in Pakistan and Afghanistan whenever U.S. missiles have been fired. The region is too dangerous for outsiders to enter, making independent confirmation of the attack's details impossible.

Militant leaders have been targeted in dozens of strikes in the past two years from U.S. drones, high-tech, remote control planes used for both surveillance and to fire Hellfire missiles. The U.S. military never comments on such operations. The highest known death toll in earlier suspected U.S. missile strikes in Pakistan was 30.

Pakistan has loudly disapproved of past drone attacks because they involve the use of force by a foreign government on its soil and sometimes kill innocents.

But the latest strikes went unremarked upon by Pakistani officials for almost 24 hours. When the AP asked for comment, the Foreign Ministry issued a short statement reiterating "Pakistan's consistent position that drone attacks are a violation of Pakistan's sovereignty and must be stopped."

Pakistani officials have said previously that civilian casualties occurred when the U.S. struck suspected targets on the Afghan border without Pakistan's agreement and intelligence.

At least two of those targets — Sirajuddin Haqqani and Maulvi Naseer — are fighting U.S. troops in Afghanistan, but Pakistan has no quarrel with either man.

This time, the apparent U.S. target was Pakistan's most wanted man and the focus of a military operation that is gearing up in his home territory of South Waziristan, part of the lawless tribal zone where Usama bin Laden and other high-value U.S. targets may be hiding.

The offensive comes on the back of the army's operation to oust the Taliban from another northwestern stronghold in the Swat Valley region.

Both campaigns are strongly backed by the Obama administration, which views them as a test of Pakistan's resolve to confront a growing insurgency after years of halfhearted offensives and peace deals with militants.

Many Pakistanis support the operations, fed up with the brutality the Taliban displayed in Swat and with Mehsud's increasingly widespread and bloody campaign of bombings that have killed not just security forces, but also civilians and Islamic clerics who denounced the militant violence as against the tenets of Islam.

Mehsud is also accused of engineering last year's assassination of former Prime Minister Bhutto, whose husband, Asif Ali Zardari, is now president of Pakistan.

The battle in the tribal zone, a mountainous area where the central government holds little sway over heavily armed and religiously conservative clans, will almost certainly be far tougher than in Swat.

Mehsud is believed to have some 12,000 loyal fighters, including hundreds of foreigners. He humbled the Pakistani army in past battles and has been forging fresh alliances with other powerful Taliban leaders and killing off opponents — the most recent one on Tuesday.

"Baitullah Mehsud has crossed a red line, and the Pakistan government and military is declaring open war on him," said Ishtiaq Ahmad, a Pakistan-U.S. specialist at Islamabad's Qaid-i-Azam University.

"What we are seeing now is a relatively promising scenario where there is renewed commitment and closer collaboration between Pakistan's security forces and NATO and U.S. forces in Afghanistan," he said.

That tone could change, however, if the attacks kill leaders less disliked than Mehsud and his cohorts, Ahmad said.

Mahmood Shah, a former security chief in the tribal region, said the government's failure to condemn the missile attacks forcefully could produce a backlash if the U.S. is perceived to be fighting Pakistan's battles.

"Once the impression is established that Americans are assisting in this operation, the indigenous effort will be discredited and anti-American sentiments in the tribal region will overshadow everything," Shah said.