The U.S. is pledging «immediate support» of South Korea as part of a «firm» commitment to defend its ally under America's nuclear umbrella, stronger language than in last year's version of their long-standing policy statement, according to AP. Noting North Korea's nuclear test Oct. 9, Defense Secretary Donald H. Rumsfeld and South Korean Defense Minister Yoon Kwang-ung «demanded that North Korea refrain from any further action that might aggravate tensions,» according to the joint communique made public Saturday. Both sides agreed that North Korea's «continued development» of weapons of mass destruction and long-range missiles, and the threat of proliferation were «a challenge» to the alliance between the United States and the Republic of Korea, the defense chiefs said in the statement. It said Rumsfeld «offered assurances of firm U.S. commitment and immediate support» to South Korea, including continuation of the extended deterrence offered by the protective umbrella of the U.S. nuclear arsenal.