Pakistan blocks NATO trucks after deadly strike

BRIAN WILLIAMS, anchor (Washington, DC): Relations between the United States and Pakistan may be at a new low tonight, and that tension is not a good thing for the US strategy against terrorism. Pakistan has now blocked a vital supply route into Afghanistan after a helicopter strike killed three Pakistani troops along the border. Pakistanis say it was a NATO chopper that unleashed that strike. Our own John Yang is on duty tonight in Kabul . John , good evening.

JOHN YANG reporting: Good evening, Brian . Tonight, General David Petraeus , the top US commander here, has reached out to officials in Pakistan to offer his condolences for the deaths, but NATO officials aren't yet ready to accept responsibility. Pakistan wasted no time responding to the deaths of these three soldiers killed at a border post in Pakistan's tribal region by Apache attack helicopters. The choppers were supporting ground forces in Afghanistan , who thought they spotted insurgents firing mortars. NATO officials say the Apaches took small arms fire from inside Pakistan . Brigadier General JOSEF BLOTZ ( International Security Assistance Force Spokesman): Operating in self-defense, the ISAF aircraft entered into Pakistani airspace, killing several armed individuals.

YANG: Within hours Pakistan blocked US and coalition supply trucks heading into Afghanistan . Late today more than 150 trucks were backed up in the Khyber Pass . The Torkham border crossing is on a vital supply line from Karachi . It handles about 80 percent of the military 's fuel, food, water and other non-lethal supplies bound for bases in Afghanistan . Anti-American sentiment is strong in Pakistan as cross border attacks are at an all-time high. Today, the Pakistani prime minister pressed the issue with visiting CIA director Leon Panetta . Another official wondered whether the West was an ally or an enemy.

Mr. REHMAN MALIK (Pakistan Interior Minister): If you are being attacked, so are you fighting a war or are you in war together?

YANG: The Pakistani partnership is vital to the Afghan war effort. Since 2001 , the United States has given Pakistan 's military more than $10 billion to help it fight insurgents. Fueling tensions between the two nations, cell phone video has surfaced purporting to show Pakistani soldiers of the Swat valley killing blindfolded civilians. Today, Pakistani military officials told NBC News they're investigating and suggested the videos were staged to discredit them. Tonight, NATO officials say that border crossing would have to be closed for some time before troops begin to feel the pinch, but one told me they are actively looking for a way to bypass Pakistan with those supplies altogether.

Brian: John Yang at our NBC News bureau in Kabul tonight. John , thanks.

WILLIAMS: