South Korean President Lee Myung Bank Friday urged North Korea to stop its "reckless military provocation," in a speech to mark the 60th anniversary of the outbreak of the Korean War, reports said, according to dpa. Tensions have been rising between the two Koreas since the sinking of a South Korean Navy vessel in March, causing the death of 46 sailors. International investigators concluded the ship was sunk by a North Korean torpedo. "Our ultimate goal is not a military confrontation but peaceful reunification," Lee was quoted as saying by the South Korean Yonhap News agency. The president was speaking at a ceremony to remember the 1950-53 conflict, which ended with an armistice and has never been the subject of a formal peace treaty. Thousands of war veterans and others gathered in Seoul for the ceremony, as the president again called on Pyongyang to apologize for the March 26 sinking of the Cheonan in the Yellow Sea. Seoul has taken the case to the United Nations Security Council. North Korea has denied all involvement in the sinking of the 1,200-ton patrol ship, and has threatened military relation if any punitive measures are taken. In his speech, Lee commemorated the "sacrifice and dedication" of South Korean and the UN troops from 21 nations who supported them, calling them "a cornerstone of South Korea's history." "The Cheonan incident remined us of the sad reality of the divided South and North," Defense Minister Kim Tae Young said at a separate ceremony at the War Memorial hall. During the ceremony, the top US commander in South Korea, General Walter Sharp, vowed to deter and defeat any further provocations by North Korea. "True peace cannot exist when North Korea resorts to force and violence," Sharp said. "The North Korean leadership must know that any further provocations will be dealt swiftly and decisively," Sharp warned. North Korean troops invaded South Korea on June 25, 1950. According to historians' estimates more then 3 million people, among them 2.5 million civilians died on both sides during the war.