WASHINGTON (CNN) -- President Bush authorized U.S. special forces to conduct ground assaults inside Pakistan without seeking Islamabad's permission first, a senior American intelligence official said Thursday.
Adm. Mike Mullen, chairman of the Joint Chiefs, said better U.S.-Pakistan cooperation is needed to fight terror.

"We have had the president's OK for months," said the official, who declined to be identified because the order is classified. "It is my understanding that the Pakistanis are well-aware of the change."
The official would not elaborate on the exact nature of the order.
The official says Pakistan's leaders will be notified during an assault or after the fact, depending on the situation but "most definitely after a decision has been made and things set in motion."
National Security Council spokesman Gordon Johndroe declined to comment on the report.
Thursday's report comes after a statement from Pakistan's armed forces chief on Wednesday that no foreign forces will be allowed to operate inside Pakistan.

Pakistan's "territorial integrity ... will be defended at all cost and no external force is allowed to conduct operations ... inside Pakistan," according to a military statement attributed to Chief of Army Staff Gen. Parvez Kayani -- who succeeded Pervez Musharraf after he stepped down as Pakistan's army chief last year.
A senior U.S. official said last week that U.S. helicopters dropped troops in the village of Angoor Adda in South Waziristan, which borders Afghanistan.
Local media reports said the troops came out of a chopper and fired on civilians. The U.S. official said there may have been a small number of women and children in the immediate vicinity, but when the mission began, "everybody came out firing" from the compound.
Pakistan summoned the U.S. ambassador in Islamabad to complain about the incident, which it said killed 15 civilians. It called the raid "reckless."
Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said Wednesday that the United States and Pakistan must increase cooperation to battle al Qaeda and Taliban militants that are using areas along Pakistan's border with Afghanistan as a safe haven.

Mullen stressed that Afghanistan can't be referenced without "speaking of Pakistan," where, he said, the militant groups collaborate and communicate better, launch more sophisticated attacks, employ foreign fighters and use civilians as human shields. Watch how Pakistan is trying to fight militants »
"In my view, these two nations are inextricably linked in a common insurgency that cs the border between them," he said, adding that he plans "to commission a new, more comprehensive strategy for the region, one that covers both sides of the border."