South Korea ? South Korea accused North Korea today of firing a torpedo that sank a naval warship in March, killing 46 sailors in the country’s worst military disaster since the Korean War.

President Lee Myung-bak vowed “stern action” for the provocation following the release of long-awaited results from a multinational investigation into the incident. North Korea, reacting swiftly, called the results a fabrication and warned that any retaliation would trigger war.

Investigators said evidence overwhelmingly proves North Korea fired a homing torpedo that caused a massive underwater blast that tore the Cheonan into two on March 26. Fifty-eight sailors were rescued from the frigid Yellow Sea waters near the Koreas’ maritime border, but 46 perished.

“(We) will take resolute countermeasures against North Korea and make it admit its wrongdoings through strong international cooperation,” Lee told Australian Prime Minister Kevin Rudd in a phone conversation, the presidential office said.

The White House called the sinking an unacceptable “act of aggression” that violates international law and the truce signed in 1953.