WASHINGTON (Reuters) - The aggressive U.S. campaign of drone strikes inside Pakistan will not ease despite the killing of Osama bin Laden, even as the unilateral action infuriates Pakistanis and further strains diplomatic ties.
Washington will continue hitting Pakistan-based militants blamed for attacks on U.S. soldiers in neighboring Afghanistan, current and former U.S. officials said.
The use of missile-armed Predator drones to attack militants has widened a diplomatic divide with Pakistan and sharpened anti-U.S. anger -- but killed few senior militants.
The Pentagon, however, sees the drones, unmanned aerial vehicles that can fly for hours at a time, as a key weapon for disrupting al Qaeda and other militants in tribal areas where Pakistan's government has little control.
The bin Laden operation -- so secret Pakistan was kept in the dark -- appears to have strengthened the hand of those within the Obama administration, notably in the intelligence community, who have advocated going around Pakistan when attacking al Qaeda and other militants.
"There are absolutely no plans at present to cease or scale back U.S. counterterrorism operations in Pakistan," one U.S. official said on condition of anonymity. "Efforts to thwart terrorism will continue."
The strikes lay bare the challenge Washington faces with Pakistan as it seeks to stabilize Afghanistan, where Obama hopes to begin withdrawing troops this summer despite record violence. The United States is also trying to avoid undermining nuclear-armed Islamabad's weak civilian leadership.
"The question is whether Pakistan will continue to tolerate the drones," an aide in the U.S. House of Representatives said on condition of anonymity.
"As long as we can get away with it as a convenience, and Pakistan doesn't object too much, we'll do it."
A senior Pakistani security official, asked if Pakistan would take steps to stop the strikes, said there was "nothing of that sort" under way to derail the drone program.
"You have to realize that all (the) equipment you use is theirs, so you can't afford confrontation with them," the official said on condition of anonymity.
The strikes, launched remotely from sophisticated Predator aircraft, were intensified beginning in July 2008 as frustration mounted in the Bush administration at Pakistan's lukewarm pursuit of Taliban and other militants operating from Pakistan's lawless western tribal regions.
Obama, who adopted a tougher line on Pakistan when he took office in January 2009, has redoubled the tempo of the strikes. Since that time, drones have killed around an estimated 1,400 militants, and close to 100 civilians, according to a tally by the Long War Journal, a military blog.
Despite the anger unleashed in Islamabad by the May 2 raid on bin Laden's compound in Pakistan, Washington did not hesitate to resume the strikes. Only four days later, it launched a series of drone attacks killing at least 17 suspected militants in North Waziristan.
U.S. intelligence officials favor the strikes because they do not endanger American lives and allow the United States to sidestep Islamabad's seeming unwillingness to disrupt militant groups not seen as a threat to Pakistan.
"The drone strikes have been a powerful tool to disrupt al Qaeda operations in tribal areas," where the Pakistani military has only a limited presence, said Lisa Curtis, a former CIA analyst and State Department official now at the Heritage Foundation in Washington.
Obama weighed the option of a drone strike on bin Laden's compound. His decision to instead dispatch elite commandos raises new questions about the program's effectiveness and its drawbacks.
The strikes have failed to kill the most wanted insurgents, even as they expose local military and civilian leaders to mounting public fury over what many Pakistanis see as a flagrant violation of their national sovereignty.
Senior Democratic Senator John Kerry, who is a de facto U.S. envoy to Pakistan, warned last week that Pakistani leaders could pay a high price for being seen as tacitly accepting a missile program that has killed Pakistani civilians.
Vali Nasr, who until last month was a senior State Department adviser on Pakistan, said Islamabad may ask Washington to halt its counterterrorism activities in Pakistan, including drone strikes, because they "are no longer politically viable for the Pakistani government."
"We are very happy about this operation, but it will actually make continuation of most of our counterterrorism programs far more difficult. It was almost like a one-shot deal that came at a high cost," he said.
If Pakistan is willing to gamble billions of dollars in U.S. aid, it might permanently shut down the U.S. ability to launch drones from western Pakistan, forcing Washington to launch the aircraft from even less secure Afghanistan.
Pakistan might also make it harder for CIA officials to enter the country or close down NATO's main supply route for its campaign in Afghanistan.
Since 2001, Congress has approved about $20 billion in direct U.S. aid and military reimbursement for Pakistan, and the Obama administration has requested about $3 billion in military aid for the next fiscal year.
The calculus in Islamabad could change, however, if U.S. lawmakers follow through with threats to reduce aid or if simmering discontent in Pakistan intensifies.
"I don't know where that threshold is," Nasr said. "The military cannot be seen as not reacting -- some of this will be theater to placate public opinion, and some of it will be real to show they're in control of their own house."
Additional reporting by Augustine Anthony, Kamran Haider and Rebecca Conway in Islamabad and Mark Hosenball and Susan Cornwell in Washington; editing by Mohammad Zargham