U.S. vows all-out defense against 'grave' North Korean threat

By David Brunnstrom and Arshad Mohammed WASHINGTON (Reuters) - The United States and South Korea agreed on Wednesday to step up military and diplomatic efforts to counter North Korea's nuclear and missile programs, saying they posed a "grave" security threat following repeated tests this year. After talks in Washington between their foreign and defense ministers, the countries said they had agreed to set up a high-level Extended Deterrence Strategy and Consultation Group to leverage "the full br