The United States military is quietly carrying out the largest military offensive in Afghanistan since U.S. troops invaded the country in 2001. "The Taliban has made a comeback, and we have the next 90 days to crush them," said a senior U.S. military official. The offensive, "Operation Mountain Thrust," involves almost 11,000 U.S. troops and is focused on four southern Afghanistan provinces. The Taliban has re-emerged as the Afghan government "has created vacuums of power" says the official. Proceeds from the growing opium trade in the region has helped the Taliban obtain new weapons and pay local officials. The Taliban leader, Mullah Omar, remains at large despite a $10 million reward offered by the United States. U.S. military officials believe he has established a safe haven in Pakistan, where U.S. soldiers cannot operate.