“Now we have a fully equipped air defense system on the Afghan border. It has the capability to trace and detect any aircraft,” the official in the northwestern city of Peshawar.

The official said the step had been taken to avert air incursions from Afghanistan and to respond to any future air strikes. “The system has also been upgraded to immediately respond after detecting any aircraft or helicopter and to shoot it down,” he added.

Pakistan deployment of air defense weapons at the border shows just how much distrust exists between the country and US-led forces fighting in Afghanistan, even though Islamabad has received billions of dollars in American aid over the last decade. Pakistan shut its border to NATO supply convoys on Nov. 26, the same day as the deadliest single cross-border attack of the 10-year war in Afghanistan.

The government also ordered the United States to leave the Shamsi Air Base in the southwest, widely reported as a hub in the covert CIA drone war against the Taleban and Al-Qaeda in Pakistan’s border area with Afghanistan. Pakistan gave tacit support to the program, but no US drone strike has been reported on Pakistani soil since Nov. 17.

The Nov. 26 attacks brought the fragile Pakistani-US alliance to a fresh low, already reeling from an American stealth raid that killed Al-Qaeda leader Osama Bin Laden near the Pakistani capital on May 2.

A senior Pakistani military officer said the NATO airstrike last month was preplanned and warned of more attacks,comments likely to fuel tension with the United States.

Maj. Gen. Ashfaq Nadeem, director general of military operations, was also quoted by newspapers on Friday as saying that Pakistan, a strategic US ally, would deploy an air defense system along the border to prevent such attacks. The Daily Times said Nadeem described the attack as a plot. Another newspaper quoted him as saying it was a "preplanned conspiracy" against Pakistan.

"We can expect more attacks from our supposed allies," the Express Tribune quoted Nadeem as saying at the senate briefing.

Pakistan army chief Gen. Ashfaq Pervez Kayani has instructed troops on the ground that they are allowed to strike back against any future incursions without prior approval of top commanders, Qazi quoted Nadeem as saying.