President Bush secretly approved more aggressive cross-border operations in July, current and former American officials have told the Associated Press.
Since Aug. 13, there have been at least seven reported missile strikes as well as a raid by helicopter-borne US commandos that Pakistani officials claim killed 15 civilians in tribally governed territory where the government has little control. The frontier region is considered a likely hiding place for Osama bin Laden and his deputy, Ayman al-Zawahri.
Pakistan's government and military have issued stiff protests to Washington over the recent rash of cross-border strikes, although the criticism appeared to be mostly rhetoric aimed at soothing domestic anger, given that Pakistan has few options for stronger action.
Domestic media have criticized the government for not reacting more strongly, even suggesting the public criticism is just lip service and that a secret deal has been reached with Pakistan's leadership allowing cross-border incursions.
General Ashfaq Parvez Kayani, the Pakistani Army chief, has denied that and vowed to protect the country's sovereignty "at all cost."
Leaders, including new President Asif Ali Zardari, have reiterated their commitment to fighting violent Islamic extremism and have aired no threats to withdraw their cooperation.
However, they are sensitive to public opinion in Pakistan, which is hostile to US policy in the region.
Agitation on the issue by former Prime Minister Nawaz Sharif, who heads the main opposition party and has a large popular following, could make it hard for Islamabad to maintain the close alliance with Washington forged by Zardari's predecessor, Pervez Musharraf.
"We need at this time to make it clear to foreign countries that Pakistan will not tolerate such actions," said Ahsan Iqbal, a lawmaker in Sharif's Pakistan Muslim League-N party. "If it continues, then Pakistan can consider pulling out completely from this war on terror."
Iqbal and another party leader called for an urgent parliament session to debate how Pakistan can respond.
