Some of the first U.S. combat operations against al Qaeda and the Taliban following the Sept. 11 attacks in 2001 were launched from a former Soviet air base in southeastern Uzbekistan called Karshi-Khanabad, also known as K2. Between 2001 and 2005, about 16,000 U.S. military and Defense Department personnel served at the base. It turns out the terrorists were not the only danger the troops faced at a site some U.S. personnel have described as a toxic wasteland.