WASHINGTON - Obama administration officials making the case for a US military response to Syria's alleged gassing of its citizens are invoking another American foe long suspected of stockpiling chemical weapons: North Korea.The specter of North Korea hovered over US congressional debate this week as President Barack Obama's top security aides sought authorization for what they said would be the limited use of force in Syria, arguing that failure to act would embolden Pyongyang and others.Crisis in Syria - full JPost.com coverageThe focus of US diplomacy with North Korea has been its expanding nuclear weapons and ballistic missile programs. But Hagel told US lawmakers that Washington and Seoul were also concerned about chemical weapons."I just returned from Asia, where I had a very serious and long conversation with South Korea's defense minister about the threat that North Korea's stockpile of chemical weapons presents to them," Hagel told the House Foreign Affairs Committee. He described the North Korean stockpile as "massive."Like much about secretive North Korea, relatively little is known about the current state of the country's chemical weapons industry.North Korea is one of five countries that have not signed the Chemical Weapons Convention. Pyongyang denies having chemical weapons, and North Korea's relatively new leader Kim Jong-un, has made no public mention of such a capability."No reliable information is available concerning recent chemical weapons activity within (North Korea)," wrote Joseph Bermudez, publisher and editor of the KPA Journal, a specialist publication on the North Korean military, in a new monograph.'POLICY OF AMBIGUITY'South Korean estimates form the basis of most public assessments of North Korea's chemical weapons stockpiles. The 2010 Defense White Paper by the South Korean Ministry of National Defense estimates that North Korea has between 2,500 and 5,000 metric tons of chemical weapons agents.The stockpiles include the nerve gas sarin, which the United States accuses Syria's government of using last month, as well as mustard gas, phosgene and hydrogen cyanide, the paper said.In a 2009 threat assessment to the Senate Armed Services Committee, Lieutenant General Michael Maples, then director of the Defense Intelligence Agency, said "North Korea's chemical warfare capabilities probably includes the ability to produce bulk quantities of nerve, blister, choking and blood agents."Bermudez says there have been repeated reports since the 1990s of North Korea supplying chemical weapons-related agents or technology to Egypt, Iran, Libya and Syria, mostly in the form of chemical warheads for Scud missiles.Japan's Sankei Shimbun newspaper reported last month that in April, Turkish authorities stopped the Libya-flagged ship El Entisar that was carrying gas masks bound for Syria. A cargo of 14,000 protective suits from North Korea was seized in 2009 by Greece on a ship believed to be bound for Syria, Bermuda wrote.But Bermudez cautions that "these reports, while numerous, remain to be confirmed."Many analysts suggest North Korea's steep economic decline in the past two decades has taken a toll on the chemical sector that produces precursor ingredients for weapons.Karl Dewey, a weapons analyst at IHS Jane's in London, says it's "hard to tell, but that's in keeping with the North Korean policy of ambiguity."North Korea's "military-first" policy prioritizes warfare capabilities over the civilian economy, so amid economic hardship "production may have ceased or slowed, but it won't have diminished their stockpile altogether," Dewey said.In April, the US Army moved its 23rd Chemical Battalion with nuclear, biological, and chemical reconnaissance and decontamination capabilities back to South Korea, more than eight years after it was withdrawn, the service said on its website."North Korea is hoping for ambivalence from the Congress," Secretary of State John Kerry told the House Foreign Affairs Committee on Wednesday.Defense Secretary Chuck Hagel cited North Korea as a country that he said could be emboldened if global norms against use of chemical weapons are weakened by US inaction in response to the Aug. 21 attack that killed more than 1,400 people in the suburbs of Damascus.