Pakistan has decided to re-open supply routes that the United States and its allies have used to supply their troops in Afghanistan, U.S. Secretary of State Hillary Clinton said Tuesday.

Pakistan shut down the supply routes - stretching from Afghanistan through the lawless western tribal regions of Pakistan and down to the southern port of Karachi - last November after dozens of its troops were killed in a mistaken U.S. airstrike. Clinton said Tuesday she offered her "deepest regrets" to Pakistani Foreign Minister Hina Rabbani Khar for the "tragic incident."

"This is a tangible demonstration of Pakistan’s support for a secure, peaceful, and prosperous Afghanistan and our shared objectives in the region," Clinton said. "This will also help the United States and ISAF conduct the planned drawdown at a much lower cost. This is critically important to the men and women who are fighting terrorism and extremism in Afghanistan."

The routes offer a shorter and more direct route than the one NATO has been using since November that goes through Russia and other nations and avoids Pakistan altogether. The supply route will take on more significance as NATO troops prepare to depart Afghanistan by 2014 and will have to move heavy equipment and supplies out of Afghanistan for shipment from Karachi.