ISLAMABAD, Pakistan - Two suicide bombers killed at least 64 people outside Pakistan's biggest weapons factory yesterday in the deadliest attack by the Taliban since they began hitting Pakistani government sites with suicide bombers more than 18 months ago.
The Taliban said the bombings were in response to a fierce Pakistani military campaign, including fighter jets and helicopter gunships, that has unfolded over the past two weeks in the tribal region of Bajaur.
The insurgents warned of more attacks if the government continued its campaign, which the military says has forced some 200,000 people to flee their homes.
Following the resignation of President Pervez Musharraf on Monday, the twin suicide bombings underscored the Taliban's determination to safeguard their strongholds in the lawless tribal areas, no matter who holds power in Islamabad.
Musharraf, who until December was army chief as well as president, was reviled by the militants, who at least twice tried to assassinate him. He was also unpopular with the public for sometimes using heavy force in the tribal regions.
The current civilian government, elected in February, promised negotiations in hopes of gaining a reprieve.
Early this year, the military struck fresh peace deals with the militants, pulling the army back from sections of the tribal regions.
The fighting in Bajaur has been the most intense since then, and the Taliban attacks yesterday made it clear that, even with Musharraf gone, any attempt to challenge the militants' strongholds would be met with retaliation - suicide bombings aimed at bringing the insurgent war home to the heart of Pakistan.
Pakistanis suffered 56 suicide attacks last year, killing more than 400 civilians. The previous biggest attack came during the election campaign in February, when a suicide bomber blew himself up at a rally in the tribal areas, killing 55 people, according to a tally by the daily newspaper Dawn.
The attack yesterday was directed against the Pakistan Ordnance Factories, a complex of more than 16 factories with about 20,000 workers.
It seemed timed to cause maximum casualties, coming as it did during the afternoon change of shifts.
The complex, which makes ammunition, rifles, pistols and explosives both for the Pakistani army and for export, is only about 20 miles north of the capital, at a place called Wah.
A retired general who headed the ordnance factory at Wah, Talat Masood, said that in choosing the weapons complex, the Taliban had deliberately selected a symbolically important industry, and one that Pakistanis thought was virtually impregnable.
The insurgents were also intent, Masood said, on trying to intimidate the four-month-old civilian government, which is already in deep disarray and has paid scant attention to the insurgency.
"They are trying to give a signal that they can hit at any defense installation," he said of the Taliban. "And they are intensifying the pressure on the civilian government to stop the Bajaur operation."
Since Musharraf's resignation Monday, the leaders of the two main political parties, Asif Ali Zardari and Nawaz Sharif, have been embroiled in an intense power struggle over who should replace the president. The two men increasingly appear headed for a split.
Zardari, who leads the majority party in the coalition, the Pakistani Peoples Party, and who has declared that he wants to be president, issued a statement deploring the attack at the weapons plant.
In Parliament, Prime Minister Yousaf Raza Gilani said that the government would not talk to "militants who are threatening peace," but added that it would keep up a "dialogue" with the people of the tribal areas.