The C.I.A. has drastically increased its bombing campaign in the mountains of Pakistan in recent weeks, American officials said. The strikes are part of an effort by military and intelligence operatives to try to cripple the Taliban in a stronghold being used to plan attacks against American troops in Afghanistan.
As part of its covert war in the region, the C.I.A. has launched 20 attacks with armed drone aircraft thus far in September, the most ever during a single month, and more than twice the number in a typical month. This expanded air campaign comes as top officials are racing to stem the rise of American casualties before the Obama administration’s comprehensive review of its Afghanistan strategy set for December.
The strikes also reflect mounting frustration both in Afghanistan and the United States that Pakistan’s government has not been aggressive enough in dislodging militants from their bases in the country’s western mountains. In particular, the officials said, the Americans believe the Pakistanis are unlikely to launch military operations inside North Waziristan, a haven for Taliban and Qaeda operatives that has long been used as a base for attacks against troops in Afghanistan.
Beyond the C.I.A. drone strikes, the war in the region is escalating in other ways. In recent days, American military helicopters have launched three airstrikes into Pakistan that military officials estimate killed more than 50 people suspected of being members of the militant group known as the Haqqani network, which is responsible for a spate of deadly attacks against American troops.
Such air raids by the military remain rare, and officials in Kabul said Monday that the helicopters entered Pakistani airspace on only one of the three raids, and acted in self-defense after militants fired rockets at an allied base just across the border in Afghanistan. At the same time, the strikes point to a new willingness by military officials to expand the boundaries of the campaign against the Taliban and Haqqani network — and to an acute concern in military and intelligence circles about the limited time to attack Taliban strongholds while American “surge” forces are in Afghanistan.
Pakistani officials have angrily criticized the helicopter attacks, saying that NATO’s mandate in Afghanistan does not extend across the border in Pakistan.
As evidence of the growing frustration of American officials, Gen. David H. Petraeus, the top American commander in Afghanistan, has recently issued veiled warnings to top Pakistani commanders that the United States could launch unilateral ground operations in the tribal areas should Pakistan refuse to dismantle the militant networks in North Waziristan, according to American officials.
“Petraeus wants to turn up the heat on the safe havens,” said one senior administration official, explaining the sharp increase in drone strikes. “He has pointed out to the Pakistanis that they could do more.”
Special Operations commanders have also been updating plans for cross-border raids, which would require approval from President Obama. For now, officials said, it remains unlikely that the United States would make good on such threats to send American troops over the border, given the potential blowback inside Pakistan, an ally.
But that could change, they said, if Pakistan-based militants were successful in carrying out a terrorist attack on American soil. American and European intelligence officials in recent days have spoken publicly about growing evidence that militants may be planning a large-scale attack in Europe, and have bolstered security at a number of European airports and railway stations.
“We are all seeing increased activity by a more diverse set of groups and a more diverse set of threats,” said Homeland Security Secretary Janet Napolitano before a Senate panel last week.
The senior administration official said the strikes were intended not only to attack Taliban and Haqqani fighters, but also to disrupt any plots directed from or supported by extremists in Pakistan’s tribal areas that were aimed at targets in Europe. “The goal is to suppress or disrupt that activity,” the official said.
The 20 C.I.A. drone attacks in September represent the most intense bombardment by the spy agency since January, when the C.I.A. carried out 11 strikes after a suicide bomber killed seven agency operatives at a remote base in eastern Afghanistan.
According to one Pakistani intelligence official, the recent drone attacks have not killed any senior Taliban or Qaeda leaders. Many senior operatives have already fled North Waziristan, he said, to escape the C.I.A. drone campaign.
Over all the spy agency has carried out 74 drone attacks this year, according to the Web site The Long War Journal, which tracks the strikes. A vast majority of the attacks — which usually involve several drones firing multiple missiles or bombs — have taken place in North Waziristan.
The Obama administration has enthusiastically embraced the C.I.A.’s drone program, an ambitious and historically unusual war campaign by American spies. According to The Long War Journal, the spy agency in 2009 and 2010 has launched nearly four times as many attacks as it did during the final year of the Bush administration.
One American official said that the recent strikes had been aimed at several groups, including the Haqqani network, Al Qaeda and the Pakistani Taliban. The United States, he said, hopes to “keep the pressure on as long as we can.”
But the C.I.A.’s campaign has also raised concerns that the drone strikes are fueling anger in the Muslim world, potentially creating another generation of militant operatives.
This year, the man who attempted to detonate a truck filled with explosives in Times Square told a judge that the C.I.A. drone campaign was one of the factors that led him to train with Pakistani militants and launch an attack against the United States.
In a meeting with reporters on Monday, General Petraeus indicated that it was new intelligence gathering technology that helped NATO forces locate the militants killed by the helicopter raids against militants in Pakistan.
In particular, he said, the military has expanded its fleet of reconnaissance blimps that can hover over hide-outs thought to belong to the Taliban in eastern and southern Afghanistan.
The intelligence technology, General Petraeus said, has also enabled the expanded campaign of raids by Special Operations commandos against Taliban operatives in those areas.
Rod Nordland and Alissa J. Rubin contributed reporting from Kabul, Afghanistan, and Ismail Khan from Peshawar, Pakistan.
This story, "C.I.A. steps up drone attacks within Pakistan," first appeared in the New York Times.