U.S. and Japanese leaders have agreed to jointly respond to North Korea's sinking of South Korea's “Cheonan” warship.

Japan's Kyodo News says U.S. President Barack Obama and Japanese Prime Minister Yukio Hatoyama talked on the phone Friday and confirmed their plans to respond jointly to Pyongyang’s provocation.

The two sides announced last week after talks between U.S. Secretary of State Hillary Clinton and Japanese Foreign Minister Katsuya Okada that Seoul, Tokyo and Washington have all agreed to strengthen their alliance in order to deal with North Korea.