The United States, South Korea and Japan should reassess whether American "extended deterrence" is still strong enough to counter growing nuclear threats from North Korea, a former top U.S. military commander said Monday.

Dennis Blair, chairman of Sasakawa USA, who had served as U.S. Pacific commander, made the suggestion in a joint article with former Japanese military general Masayuki Hironaka, saying NATO still maintains American nuclear warheads.

"Extended deterrence" refers to the threat of nuclear retaliation to deter attacks on allies. The U.S. has provided extended deterrence or a "nuclear umbrella" to allies South Korea and Japan after withdrawing nuclear warheads from South Korean in the early 1990s.

"The United States, Japan and Korea must reassess whether American extended deterrence in East Asia is still strong, or whether additional measures are needed," Blair said in the article contributed to Diplomat magazine.

"Consider our position in Europe, where the nuclear threat from the Soviet Union was much greater, and the nuclear doctrine in Russia was more threatening, this reassurance structure was judged not to be enough," he said. "In Europe, NATO maintains both American nuclear warheads and alliance tactical nuclear forces for reassurance while the United States has withdrawn all its nuclear weapons from Korea."

After the North's fourth nuclear test last week, some members of South Korea's ruling party called for deployment of nuclear weapons in the country. But the government dismissed the idea, saying it runs counter to the principle of a nuclear-free Korean Peninsula.

Blair said that the U.S. should make an "authoritative statement" warning the North that "a major conventional attack would be defeated by combined forces of the Republic of Korea and the United States and a WMD attack would be met with a devastating retaliatory nuclear strike by the United States."

"Both alternatives would result in the end of the Kim regime," he said.

He also suggested that the U.S., South Korea and Japan come up with strong financial sanctions on Pyongyang, noting that unilateral American actions against North Korean financial transactions have been effective in the past, and trilateral sanctions would be even more damaging.

"The United States, Korea and Japan should take coordinated action that includes increasing financial sanctions on North Korea and reassessing the extended deterrence strategy to address its latest provocative action," he said. "Even if the North Korean nuclear program is not reversed, the penalties for pursuing it must be increased." (Yonhap)