ISLAMABAD, Pakistan (AP) — Pakistan’s army said Tuesday that its forces have orders to open fire if U.S. troops launch another raid across the Afghan border, raising the stakes in a dispute over how to tackle militant havens in Pakistan’s unruly border zone. Adm. Mike Mullen, the U.S. chairman of the joint chiefs of staff, arrived in Pakistan late Tuesday amid the increased tensions. Mullen planned to meet with top civilian and military leaders to discuss a range of issues, including ways to improve coordination and cooperation along the Pakistan-Afghan border.