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Months before the Obama administration said it had concluded that the Syrian government has used chemical weapons against rebels, the Pentagon began drawing on the expertise of obscure military experts to develop plans to reduce the risks from Syria’s massive stockpile of the banned munitions.

U.S. military officials were sent to Jordan to develop a range of options to keep the lethal agents from falling into the hands of extremists among the opposition or being spread throughout the region by foreign fighters aligned with the Syrian government.

According to U.S. military officials, who spoke on the condition of anonymity to describe planning, the team is evaluating scenarios that range from deploying an international coalition to secure the weapons sites to bombing storage facilities to stop the arms from falling into the wrong hands.

Part of this effort involves a $70 million program to train Jordanian security forces to identify and secure chemical weapons sites inside Syria, where one of the world’s largest stockpiles is scattered at sites across the country. Plans are also being studied for using trusted rebel groups to secure the weapons.

As part of the planning in the United States, a Maryland-based Army unit that specializes in handling chemical munitions has conducted training exercises with the 82nd Airborne Division, the Army’s rapid-response force for global crisis and the troops who would likely be first to deploy if a large ground force is required.

Timeline: Major events in Syria’s tumultuous uprising that began in March 2011.

The specialized training in containing and disposing of chemical weapons, which has gone largely unnoticed, reflects an effort by the Army to look beyond the waning years of counterinsurgency missions in Afghanistan and Iraq to develop strategies to confront emerging threats like the one posed by Syria.

“As we widen our aperture from counterinsurgency against opponents with a limited range of capabilities in Iraq and Afghanistan to full-spectrum decisive action operations against threats with some high and asymmetric capabilities across the globe, we are training to detect and mitigate chemical and biological weapons threats,” Maj. Gen. John W. Nicholson Jr., commander of the 82nd Airborne Division, said in an interview. “While we could theoretically secure such stockpiles, we would need other specialists to come in and accomplish the destruction of these stockpiles.”

The Obama administration’s decision to quietly provide weapons to selected rebel groups was based at least in part on its conclusion that the government of President Bashar al-Assad has used chemical weapons in the civil war. But even evidence cited by the administration and other Western governments does not indicate that the Syrian forces have used them on a wide basis.

Even if the weapons are not used in a large operation, U.S. officials say the final disposition of Syria’s quantities of sarin and other chemical weapons poses a vexing dilemma. In an era in which all but a handful of countries have renounced chemical weapons, the U.S. military’s relatively few chemical-weapons experts have suddenly become highly sought after.

“The United States and our allied partners have spent a lot of time thinking through the long-term disposition of these weapons when the day comes that Assad does leave power,” a senior U.S. defense official said.

The United States, which once possessed one of the largest stockpiles of chemical weapons, has extensive experience in safely handling and disposing of chemical munitions. The United States stopped producing chemical weapons during the Nixon administration and was one of the chief proponents of a 1997 treaty designed to rid the world of chemical weapons.

Since then, Army personnel have destroyed weapons such sarin, tabun and mustard gas at plants built in remote areas of the country. The work has been painstaking and fraught with risk. Engineers and chemists who come into contact with the munitions wear protective suits. Army officials designed unique assembly-line processes for each type of munition. Last year, the military eliminated the stockpiles at all but two facilities, wiping out 90 percent of the country’s chemical weapons.

“To put the nail in the coffin on something all of us fear has been incredibly fulfilling,” said Col. John Lemondes, the chemical stockpile elimination program manager at the U.S. Army Chemical Materials Activity, the agency that has done the lion’s share of the work.

Drawing in part on that work, the Army created the 20th Support Command, a unit based in Edgewood, Md., that specializes in weapons of mass destruction, including chemical munitions. Its deployable team of experts has trained with the 82nd Airborne Division this year.

“Our soldiers are trained, equipped and ready to provide wherever the nation decides to send us out,” spokesman Christopher Bush said.

Testifying before Congress last spring, Gen. Martin E. Dempsey, the chairman of the Joint Chiefs of Staff, said that securing Syria’s chemical weapons would take a “significant intervention” if it occurred amid fighting.

“If we had confidence in the opposition,” Dempsey said, “then they could secure it.” If U.S. troops took on the mission, he added, it would be in a “non-permissive environment.” The challenge would be compounded, the chairman added, because Syrians “have been moving it and the number of sites is quite numerous.”

Michael Eisenstadt, a chemical weapons expert at the Washington Institute, said there’s likely much that the West does not know about Syria’s chemical weapons program, which the Assad regime has not formally acknowledged.

“Our experience with weapons of mass destruction intelligence is very mixed,” he said. “We should not assume that what we know about the Syrian program is true. We can’t assume we have good knowledge.”