U.S. prepared to use force on North Korea 'if we must': U.N. envoy

By Michelle NicholsUNITED NATIONS (Reuters) - The United States cautioned on Wednesday it was ready to use force if need be to stop North Korea's nuclear missile program but said it preferred global diplomatic action against Pyongyang for defying world powers by test launching a ballistic missile that could hit Alaska.U.S. Ambassador to the United Nations Nikki Haley told a meeting of the U.N. Security Council that North Korea's actions were "quickly closing off the possibility of a diplomatic s