Up to 40 militants have attacked an army checkpoint, killing one soldier, a security official said on Saturday, after suicide bombers and gunmen killed dozens at a mosque near Pakistan's military headquarters.
Pakistan's army, which heavily supported militant groups in their war against Soviet occupation in Afghanistan, now faces a stubborn Taliban insurgency on its own soil and mounting US pressure to root out Islamist fighters in tribal border areas.
Soldiers at the checkpoint on a bridge in Wana, the main town in the Islamist bastion of South Waziristan, retaliated after coming under fire on Friday night, said the security official.
"There were 30 to 40 militants who first fired rocket- propelled grenades at our post and then opened fire with AK-47 rifles which killed one of our soldiers. But we retaliated and killed six militants," a security official in the region, who asked not to be named, told Reuters.
An intelligence official said helicopter gunships also hit militant positions in the battle.
The military said it made gains in a major offensive in October in South Waziristan, a global Islamist hub.
But militants have carried out retaliatory bombings since then, killings hundreds of prople and pressuring increasingly unpopular Pakistani President Asif Ali Zardari to neutralise the insurgency as he fights for his political survival.
The attack near army headquarters on Friday, which killed at least 40 people, was the biggest challenge to the writ of the state since October.
Two suicide bombers blew themselves up at a mosque frequented by military officials in the garrison city of Rawalpindi, just a 30-minute drive from the capital Islamabad, and two other militants fired on worshippers.
Interior Minister Rehman Malik described the attackers as the enemy of Islam and the country. But the army may have to find a new strategy to fight the Pakistani Taliban, disparate groups united by a common goal of taking over the nuclear-armed country and imposing their strict brand of Islamic rule.
U.S. President Barack Obama highlighted Pakistan's struggle against militants this week in outlining his plans to send 30,000 more troops to Afghanistan.
In one of his most important speeches, he called on Pakistan, the third largest recipient of US aid, to crack down harder on militants to help US troops fight the Taliban in Afghanistan. He warned that Washington would not tolerate Pakistan allowing its territory to be a safe haven for militants.
Ultimately, it is Pakistan's all-powerful military that calls the shots on setting foreign policy on Afghanistan or responding to US requests for greater cooperation on militants.
The generals have been at odds with Zardari, and his weak government has little influence. US attempts to boost cooperation have backfired in some ways.
A new $7.5 billion assistance package signed in October which reserves the right to cut off aid if Islamabad does not crack down on militants angered the military and ordinary Pakistanis who see it as a humiliating violation of Pakistan's sovereignty.