The U.S. will continue discussions on a South Korean warship which was sunk by a North Korean submarine in March with its partners in the six-nation talks, a spokesman for the U.S. State Department has said. A team of international investigators confirmed on Thursday that the 1,200-ton Cheonan corvette was sunk by a torpedo launched from a North Korean submarine. Forty-six sailors died on the night of March 26 when the ship went down near the disputed Northern Limit Line (NLL) in the Yellow Sea following a sudden explosion. "We think the results are categorical. We will obviously consult closely with the five parties as to what the appropriate next steps should be. That's one of the reasons why the Secretary will be meeting with her counterparts in Tokyo and Beijing and Seoul," Philip Crowley said. "I think one of the hallmarks of our policy towards North Korea over the past 15 months has been the strong consensus that we have had and maintained with China, with Russia, with Japan, with South Korea , on this process," the spokesman added. The six-party talks on North Korea 's nuclear program involved Russia, Japan, China, the United States and the two Koreas. They came to a halt a year ago. Crowley said the U.S. "will be guided by actions that South Korea wishes to take," but called on the North to recognize that "provocative actions will not be tolerated and that there will be consequences for those." The White House described the ship's sinking as a challenge to international peace and security. North Korea has called the results of the investigation "a fabrication." Crowley ruled out any unilateral sanctions against North Korea in connection with the sea incident. "I'm ruling out any unilateral steps. We will be consulting closely," he said. U.S. Defense Secretary Robert Gates was cautious in his statement about the investigation's findings. "The attack was against one of their ships and, naturally, they will have the lead in laying out the path forward and we will be consulting with them very closely as we move ahead," he told journalists. Joint Chiefs of Staff Chairman Adm. Mike Mullen said the status of the 28,500 U.S. troops in South Korea were "on their normal state of readiness." The conclusions of the investigation may lead to further deterioration of the already sour relations between the two Koreas and jeopardize international efforts to stop Pyongyang's controversial nuclear weapons and ballistic missile development programs. North Korea has already warned Seoul of a harsh response if the South retaliates with new sanctions against Pyongyang over the alleged attack on its warship. The two countries remain technically at war as their 1950-1953 conflict ended only in an armistice. Naval clashes between the two states over the disputed sea border took place in 1999, 2002 and last year.