By Phil Stewart
SAN FRANCISCO (Reuters) - Defense Secretary Leon Panetta warned Pakistan on Wednesday the United States would "do everything we can" to defend U.S. forces from Pakistan-based militants staging attacks in Afghanistan.
U.S. officials, including Panetta, suspect militants from the Haqqani network were behind Tuesday's rocket attack on the U.S. Embassy compound in Kabul, as well as a truck bomb last Saturday that wounded 77 American forces.
"Time and again we've urged the Pakistanis to exercise their influence over these kinds of attacks from the Haqqanis. And we have made very little progress in that area," Panetta told reporters flying with him to San Francisco.
He added, "I think the message they (the Pakistanis) need to know is: we're going to do everything we can to defend our forces."
Panetta, who was CIA director until July, has long pressed Islamabad to go after the Haqqanis, perhaps the most feared of the Taliban-allied insurgent factions fighting U.S.-led NATO and Afghan troops in Afghanistan.
He declined to answer questions about what steps the United States might take to defend U.S. forces. But Panetta said he was concerned about the Haqqanis' ability to attack American troops and then "escape back into what is a safe haven in Pakistan."
"And that's unacceptable," Panetta said.
The CIA has had success targeting militants in Pakistan using pilotless drones, and Navy SEALs killed al Qaeda leader Osama bin Laden in May during a covert raid in Pakistan. Last month, Admiral Mike Mullen, the top U.S. military officer, cited progress curtailing Haqqani movements within Afghanistan.
"I'm not going to talk about how we're going to respond. I'll just let you know that we are not going to allow these kinds of attacks to go on," Panetta said.
Pakistan's Directorate of Inter-Services Intelligence, or ISI, has long been suspected of maintaining ties to the Haqqani network, cultivated during the 1980s when Jalaluddin Haqqani was a feared battlefield commander against the Soviet Union in Afghanistan.
While based in Pakistan's North Waziristan area on the Afghan border, Haqqani refrains from attacking the Pakistani state and is seen as a way to maintain Pakistani influence in any future political settlement in Afghanistan.
U.S. officials including Panetta have played down the significance of Tuesday's attack on Kabul's diplomatic enclave, which showered rockets on Western embassies in a dramatic show of insurgent strength.
It was the longest and most audacious militant attack on the Afghan capital in the decade since the Taliban was ousted from power and a stark reminder of insurgents' resources and reach as Western forces start to return home.
Panetta stressed the attacks themselves were repelled by Afghan forces and inflicted a limited number of casualties. The U.S. military has cited gains against the Taliban in the past year, particularly in southern Afghanistan.
"These kinds of attacks -- sporadic attacks and assassination attempts -- are more a reflection of the fact that they're losing their ability to be able to attack our forces on a broader scale," Panetta said.
(Editing by Peter Cooney)