South Korea officially announced on Thursday that a North Korean submarine torpedoed one of its warships in March, a verdict that opens the path towards referring Pyongyang to the United Nations Security Council.

Shortly after the announcement, the White House issued a strong condemnation of North Korea’s attack and said it would support Seoul in its attempts to “secure justice for the 46 service members killed”. In response, Pyongyang threatened “strong measures”, including war, if the South attempted to ratchet up international sanctions.

A team of international investigators had examined the shattered wreckage of the 104-man corvette, which was ripped in two, and found traces of explosives and metal shards consistent with a North Korean torpedo.