Pakistan announced Saturday that it was immediately reopening its main border crossing with Afghanistan and that it would allow NATO to resume shipping supplies through it after a 10-day blockade left hundreds of fuel tankers and other trucks open to attacks from militants. The border is normally closed Sundays, so it seemed as if Monday would be when the flow of supplies over the northwest crossing at the Khyber Pass, near the Pakistani city of Peshawar, would resume, a U.S. Embassy spokesman, Richard Snelsire, told The Associated Press. The border dispute began after NATO helicopters hit a Pakistani border post, killing two Pakistani soldiers Sept. 30. In protest, Pakistan closed the crossing. The border closing followed strong ripostes by the Pakistani military to border actions by NATO and American forces that the Pakistani government perceives as violating its sovereignty. But the duration of the blockade and the tensions that arose between the United States and Pakistan as more than 100 trucks were torched and supplies delayed made this the worst dispute so far. As the blockade worsened, the United States, which moves about 40 percent of military supplies for its 100,000 troops through the Khyber Pass, apologized for the raid in several messages Wednesday. The American ambassador in Pakistan, Anne W. Patterson, called it a 'terrible accident'; the chairman of the Joint Chiefs of Staff, Adm. Mike Mullen, offered Pakistan's military chief, Gen. Ashfaq Parvez Kayani, a private, but official, apology; and Gen. David H. Petraeus, commander of NATO forces in Afghanistan, expressed regret for the 'tragic loss of life.' After the apologies, arsonists set fire to tankers lined up in Sibi, a town in Baluchistan, on Wednesday night. A secondary crossing at Chaman, near Quetta, remained open throughout the dispute, but heavy traffic there delayed trucks for days, and they also came under attack. Pakistani police and security forces appear to have done little to prevent the attacks, and Afghan officials suggested that the Pakistani military had even encouraged the violence to deter future NATO border strikes. The reopening was announced Saturday in a statement by Pakistan's Foreign Ministry. 