US defense chief vows 'overwhelming' response once DPRK launches nuclear weapon successfully

"The recent dramatic increase in North Korean nuclear tests and ballistic missile launches remind us of the grave threat it poses to our collective security," he said at the start of the talks with US Secretary of State John Kerry and their South Korean counterparts. The term "extended deterrence" refers to the use of US nuclear force to deter attacks on its allies.

Kerry, despite high concern and strong opposition in East Asia, said at the talks that the United States would deploy the highly controversial Terminal High Altitude Area Defense (THAAD) anti-missile system to South Korea "as soon as possible."

However, the saying that the US-built THAAD can counter the nuke and missile threat from the Democratic People's Republic of Korea (DPRK) is merely a ruse, many analysts in the region argue, fearing its deployment will only worsen the already extremely volatile situation on the Korean Penninsula.

China and Russia have expressed strong opposition to the THAAD deployment as the system far exceeds South Korea's actual defense needs and would directly threaten the strategic security of the two countries.