WASHINGTON (AP) — The White House is calling the sinking of a South Korean warship by North Korea an act of aggression that constitutes a challenge to international peace and security.

President Barack Obama's press secretary issued a statement Wednesday night after South Korea released a report concluding that the warship Cheonan was sunk by a torpedo fired by the North.

The attack last month in the Yellow Sea near the border separating the two Koreas killed 46 sailors. North Korea denies involvement in the ship's sinking.

In the White House statement, press secretary Robert Gibbs says the attack is one more instance of North Korea's unacceptable behavior and defiance of international law.