TOKYO — U.S. Secretary of State Hillary Rodham Clinton said today the evidence is "overwhelming" that a North Korean submarine sank a South Korean warship and the communist country must face international consequences for its actions.

Speaking in Tokyo at the outset of a three-nation Asian trip, Clinton said the U.S., Japan, South Korea and China are consulting on an appropriate reaction to an international investigation that blamed North Korea for the incident.

She said the report proves a North Korean sub fired a torpedo that sank the ship, the Cheonan, in March.

While it was "premature" to discuss exact options or actions that will be taken in response, Clinton said it was "important to send a clear message to North Korea that provocative actions have consequences."

"The torpedo that sunk the Cheonan and took the lives of 46 South Korean sailors was fired by a North Korean submarine," she said at a news conference with Japanese Foreign Minister Katsuya Okada.

"We cannot allow this attack on South Korea to go unanswered by the international community," she said.

North Korea denies it was responsible for the sinking and has threatened to retaliate against any attempt to punish it with "all-out war."