China should work harder to help address North Korean nuclear and missile threats if it is concerned about the THAAD missile defense system the United States wants to deploy to South Korea, a former Pentagon official said Monday.

"To the extent China is concerned that the U.S. BMD (ballistic missile defense) system or more importantly allied BMD systems have any implications for China beyond North Korea threats, frankly to me, that should be all the more incentive for China to work with us to address the North Korean threats," Daniel Chiu, former deputy assistant secretary of defense for strategy and force development, said at a seminar organized by the Asan Institute for International Policy.

The U.S. wants to deploy a THAAD (Terminal High Altitude Area Defense) missile interceptor battery to the South, where some 28,500 American troops are stationed to help defend the Asian ally against threats from the communist North.

But China sees a potential THAAD deployment as a threat to its security interests and has increased pressure in South Korea to reject such a deployment. Last week, Chinese Assistant Foreign Minister Liu Jianchao publicly said Beijing hopes Seoul will take China's concern into consideration.

"Without a North Korean threat there, we can talk about the future of missile defense but right now it's entirely unproductive to talk about what else it may be for, given the nature of the North Korean threat," said Chiu, who is now serving as a security expert at the Atlantic Council.

Van Jackson, a visiting fellow at the Center for a New American Security, also said that missile defense is a "minimum" operational counter that the U.S. can use to mitigate growing vulnerabilities to U.S. bases in South Korea and elsewhere.

"Within certain cost constraints, the more the better, and being part of an integrated system is optimal. It's not that this is going to solve our problems but this is sort of a minimum measure necessary to be able to sleep at night, to know that we're doing something more than nothing about this problem that's getting worse with time," he said.

Jackson, who also served as a senior country director for Korea at the Pentagon, also said that he had been "very much against missile defense because of its cost, because of its effectiveness or unprovenness" but such views have changed.

"It's not that those things are untrue today. It's still expensive and still largely unproven, but it's also one of the least provocative or antagonistic things you can do to mitigate vulnerability," he said. "To the extent that we are facing a very serious problem of North Korea that gets worse over time, it's kind of, this is the least we can do." (Yonhap)