Washington ( CNN ) -- An expanded team of civilian technical experts from a `` quick-reaction force '' is on the ground in Libya , tracking down and destroying `` MANPADs , '' shoulder-fired , heat-seeking missiles that the U.S. fears could be used to bring down a civilian airliner . The United States currently has a State Department officer and 14 technical experts who are embedded with munitions and destruction teams from Libya 's National Transitional Council , according to Andrew Shapiro , assistant U.S. secretary of state for political-military affairs . Officials hope to ramp up the search effort `` significantly , '' Shapiro said , with the number of specialists on the ground increasing to 50 . The joint teams are sweeping , surveying and securing stockpiles of the weapons that were previously under control of the Moammar Gadhafi regime . The joint teams already have surveyed 20 out of 36 known ammunition storage sites , a State Department official said , and have disabled or destroyed hundreds of MANPADs . The official was not authorized to speak on the record . At each site they have found from several dozen to several hundred storage bunkers . The United States estimates there were as many as 20,000 surface-to-air missiles in Libya when NATO began its operations to aid rebels in ousting Gadhafi . Shapiro declined to say how many weapons might be missing , but U.S. Gen. Carter Ham , commander of U.S. Africa Command , expressed concern that the missiles could be crossing the border . `` There are some worrying indicators ... that some of these portable air defense systems have left Libya , '' Ham said , adding that he did n't have enough information to know how many have possibly moved , `` but there 's enough ... churn out there in the information I see to cause me to be very concerned . '' U.S. officials are working with Libya 's neighbors on `` how best to address this threat , '' Shapiro said . The United States is distributing thousands of pamphlets in multiple languages , including Arabic and English , to neighboring countries , including Egypt , Algeria and Morocco , to inform their border guards what the MANPADs look like and to be on watch for any attempts to move them out of Libya . Ham noted that the MANPADs are a threat `` to anything that flies , '' including commercial airliners upon takeoff and landing . The United States also is working through NATO to alert the Libyans to stockpiles NATO was aware of and may have targeted during the conflict . `` When it comes to the conventional weapons destruction challenge , the NTC have not only have talked the talk , they 've walked the walk , '' the State Department official said . `` They have really taken leadership on this and we are committed to helping them secure the weapons stockpiles . '' The U.S. experts involved in the operation are mostly retired military personnel who were specialists in munitions handling and ordnance destruction at the Department of Defense , Shapiro said . Many of them work with nongovernmental organizations on de-mining . Shapiro noted the United States paid $ 3 million to two non-governmental organizations in Libya `` to help secure weapons that they discovered . '' CNN Pentagon correspondent Barbara Starr contributed to this report .
Gen. Ham is `` very concerned '' about proliferation across Libyan borders . A team of U.S. technical experts is assisting in securing weapons stockpiles . The United States has also provided training to the National Transitional Council, which was formed by rebel forces after Qaddafi's ouster last year. The missiles pose a threat `` to anything that flies , '' Ham says .