Pakistani government officials say senior authorities have ordered them to block oil tankers and trucks carrying Nato supplies at a checkpoint bordering Afghanistan. The two officials say they were not told the reason for the order at the Torkham border post. However, it comes after threats by Pakistani officials to stop providing protection to Nato convoys if the military alliance's choppers hit Pakistani targets again. Earlier Thursday, Pakistani officials alleged a Nato airstrike hit a border post, killing three Pakistani troops. The officials spoke on condition of anonymity because they were not authorized to release the information to the media.