Washington (CNN) -- The U.S. and NATO have been quietly talking to National Transitional Council officials for the last several weeks about securing Libya's remaining stockpiles of mustard gas and other weapons material in the event the Gadhafi regime fell, U.S. officials confirm. Topping the list of worries is Libya's stockpile of mustard gas.
"The opposition forces are being asked to keep track of what's going on" with both weapons of mass destruction (WMD) and the regime's inventory of surface-to-air missiles, a NATO official said.
"We have had direct eyes on the storage facilities" of the WMD for some time, the official said, including the use of satellites, drones and other surveillance aircraft.
The official also confirmed that intelligence personnel from the U.S. and other countries have been in Libya in recent weeks to help maintain security at various sites, although he could not confirm Western personnel are currently at those locations. "Individual nations have folks on the ground," he said.
A U.S. official also confirmed U.S. intelligence personnel have been involved in monitoring WMD stockpiles inside Libya. Both officials declined to be identified because of sensitive intelligence matters.
"We hope those items don't get out of control" of the NTC, the U.S. official said. He also noted the U.S. and NATO have told the NTC that now that it has been recognized by many countries, its personnel must conduct themselves within the realm of international law.
Congress is already underscoring the worry. "In particular, we must ensure that (Moammar) Gadhafi's stockpiles of advanced weapons, chemical weapons and explosives don't fall into the wrong hands," said Congressman Mike Rogers, R-Michigan, chairman of the House Intelligence Committee in a press statement. Rogers is also concerned about the Libyan inventory of anti tank rockets and plastic explosives.
CNN reported earlier this year that Libya still has approximately 10 tons of the deadly blister agent left in its arsenal, according to an assessment from the Arms Control Association. Much of the material has been located at the Rabta chemical weapons facility south of Tripoli.
In 2003, Libya agreed to destroy its entire chemical weapons arsenal, which included some 25 tons of mustard gas and 3,300 empty aerial bombs. The entire stock of shells and bombs was literally crushed by bulldozers in 2004.
U.S. officials say any chemical weapons material that remains in Libya would be difficult to "weaponize" into a form that could be used to conduct attacks, and it's not clear Libyan forces would follow any orders to conduct such attacks.