ISLAMABAD, Pakistan - Pakistan's Taliban on Monday vowed more attacks on tankers transporting fuel to NATO troops in Afghanistan, a move likely to prolong the closure of a vital supply route and further strain ties with ally Washington.

Angered by repeated attacks by NATO helicopters on militant targets within its borders, Pakistan blocked one of the supply routes for NATO troops in Afghanistan after one strike killed three Pakistani soldiers last week in the western Kurram region.

The incursions and the sealing of the supply route, now in its fifth day, have heightened tensions between the United States and Pakistan, whose long alliance is often uneasy.