The Pakistani Taliban has warned foreign firms to leave the country and vowed retaliatory strikes against the government after tanks, ground troops and jets were deployed in a long-awaited offensive in a troubled tribal district.
Military jets pounded targets in the country's northwest yesterday as the armed forces launched strikes against militants' safe havens that killed 37 fighters, while insurgents fought back with a roadside bomb that killed six soldiers, the first army casualties of the operation, the military said.
Prime Minister Nawaz Sharif defended the operation. "We have decided to make Pakistan as a land of peace. I believe that this operation would be the beginning of an era of peace and tranquility."
Pakistan's major cities braced for revenge attacks by ramping up security at key installations and ordering soldiers to patrol the streets, while hospitals in the northwest prepared for incoming casualties.
The offensive on North Waziristan, a stronghold of Taliban and al-Qaeda militants, was launched a week after a brazen insurgent attack on Pakistan's main airport in Karachi which left dozens dead and marked the end of a troubled peace process.
Pakistan's Western allies, particularly the United States, have long demanded an operation in the mountainous territory to flush out groups like the Haqqani network which use the area to target Nato troops in neighbouring Afghanistan.
But authorities had held back from a final push - possibly fearful of angering pro-Pakistan warlords and of opening too many fronts in their decade-long battle against homegrown Islamist insurgents.
Tehreek-e-Taliban Pakistan spokesman Shahidullah Shahid warned foreign countries to stop doing business with the government and supporting their "apostate army".
"We warn all foreign investors, airlines and multinational corporations that they should immediately suspend their ongoing matters with Pakistan and prepare to leave Pakistan - otherwise they will be responsible for their own loss," he said.
"We hold Nawaz Sharif's government and the Punjabi establishment responsible for the loss of tribal Muslims' life and property as a result of this operation," he added, vowing to "burn your palaces" in Islamabad and Lahore.
Major cities beefed up security, with troops seen patrolling the streets of Islamabad, Lahore and the economic hub of Karachi.
Police in Karachi have declared a "red alert" and cancelled leave for all 27,000 personnel, spokesman Atiq Shaikh said.
In Khyber-Pakhtunkhwa province in the northwest, which borders the tribal zone, the government had declared a state of emergency in all hospitals, provincial health minister Shahram Khan Tarakai said.
Pakistani air force jets have been pounding suspected militant hideouts since Sunday and have been joined by tanks and infantry engaging in heavy artillery strikes. In North Waziristan's main town, Miranshah, more than 2,000 troops could be seen at new posts in the mountains.
Additional reporting by Associated Press