WASHINGTON (Yonhap) -- The incoming top American military commander in Korea said Tuesday that the United States and South Korea should prepare for the possibility of a regime collapse in North Korea.



In his Senate Armed Services Committee confirmation hearing, Gen. James Thurman, the nominee to lead 28,000 U.S. forces in South Korea, raised doubts over the North's heir apparent, Kim Jong-un, who is said to be under 30.



The U.S.-South Korea Combined Forces Command "must continue readiness preparations to fight and win a war with North Korea and at the same time prepare to deal with the complexity of a regime collapse and the attendant consequences," he said.



Thurman, who has spent most of his career in field operations, stressed North Korea represents "one of the greatest near-term threats to regional security and stability."



"A significant challenge is to understand the regime of Kim Jong-il and attempt to determine its intent," he added. "The alliance must take the necessary actions to deter attack, break the cycle of North Korean provocation, and remain ready to defend if deterrence fails."



Thurman pointed out that the ongoing power succession process in the North adds "another dynamic" to deterrence. The North's leader, Kim Jong-il, is apparently working to hand over power to his third and youngest son, Jong-un, who was unknown until several months ago.



"Kim Jong-un's youth and inexperience increase the likelihood of miscalculation, as does the imperative for him to establish credibility with the military hardliners he needs to support succession," Thurman said. "These factors make him less predictable in the near term."



He said the current leader is also "unpredictable" and he is expected to continue provocations.



"I believe Kim Jong-il is an unpredictable leader. He continues to antagonize and, through his coercive diplomacy, to protect his nuclear capability, I believe," he said. "So I think he will continue this cycle of provocations."



The general expressed concerns over the North's missile and nuclear technologies, saying it possesses enough material for at least six plutonium-based weapons, along with a highly enriched uranium program, and an inventory of more than 800 ballistic missiles.



"North Korea grows closer to threatening the western United States and striking Okinawa, Guam and Alaska," he said. "This missile development program presents a threat which cannot be ignored."



He stressed that the U.S. and South Korea should bolster their joint missile defense system.



"Although there is more than one missile defense system in the ROK (South Korea), they are not mutually supporting, nor do they provide layered defense," he said, adding layered defense is required to shoot down an inbound ballistic missile at different points in its trajectory.



Sen. Carl Levin, chairman of the Armed Services Committee, noted the timing of Thurman's assignment in Korea.



"General Thurman's nomination as the next commander of U.S. forces in Korea comes at a time of significant change and simmering tension on the Korean Peninsula," the senator said at the start of the hearing.



Lt. Gen. John Allen, the nominee to be commander of U.S. forces in Afghanistan, and Vice Adm. William McRaven, tapped to lead the U.S. Special Operations Command, also attended the confirmation hearing session.



If confirmed, Thurman will replace Gen. Walter Sharp, who has served in Korea for three years.



Thurman is now commander of the U.S. Army Forces Command and served as commander of the 4th Infantry Division in Iraq from 2005 to 2006.

