Pakistani helicopter gunships involved in a bitter offensive against militants in a northwestern tribal region struck targets in a neighboring area on Sunday, a sign that the conflict may be widening to other parts of the rugged zone bordering Afghanistan. The media center for the paramilitary Frontier Corps confirmed Sunday that helicopter gunships, backed by artillery, have been pounding suspected insurgent hideouts in the Mohmand tribal area since Saturday. Mohmand is south of the Bajaur tribal region, an Al-Qaida and Taleban stronghold where the military says a three-month-old offensive has killed more than 1,600 suspected militants. Speculation has abounded that after taking control of Bajur, the military would set its sights on Mohmand. An official with the media center, who insisted on anonymity in line with military rules, said the strikes were not part of a separate offensive for Mohmand. He would not specify where in Mohmand the aircraft had attacked. Suspension of supplies to US, NATO forces Elsewhere in the northwest, Pakistan temporarily banned oil tankers and trucks carrying sealed containers from using the Khyber Pass, a move that put pressure on a vital supply line for the US and NATO forces in Afghanistan. The suspension of specific vehicles along the Khyber Pass comes just days after a band of militants hijacked around a dozen trucks whose load included Humvees intended for foreign forces in Afghanistan. The hijacking near the entrance of the famed pass highlighted the vulnerability of a critical supply line for the US and NATO in Afghanistan. Government official Bakhtiar Khan said that security concerns had prompted the suspension, but that it could be lifted as early as Monday.“The suspension was made to review the security arrangements and that has already been done,” he said. “We have issued orders to deal with attackers and snatchers more strictly.” Khan said security forces have been told they can fire upon groups of armed men trying to attack or snatch shipments.