U.S. Secretary of State Hillary Clinton says the world has a duty to respond to the sinking of a South Korean warship that has been blamed on North Korea.
Clinton made the remarks Wednesday in Seoul, where she held brief talks with South Korean President Lee Myung-bak and Foreign Minister Yu Myung-hwan.
She called the deadly March 26 attack on the Cheonan a "provocation" which requires a "strong but measured response."
Clinton also called on China to carefully study all documents relating to the sinking of the Cheonan so it can "really understand the details. "
In Beijing, Chinese Vice Foreign Minister Zhang Zhijun said the government was carefully looking at the facts of the case.
Forty-six South Korean sailors were killed when the Cheonan exploded and sank. An international investigation showed the ship was struck by a North Korean-made torpedo. North Korea denies responsibility for the incident and the dispute about the sinking has prompted Pyongyang to sever all relations with its neighbor.
North Korea said early Wednesday that it had shut down its maritime communications links with South Korea, following Tuesday's announcement that it will have no ties with Seoul while South Korean President Lee Myung-bak is in office. Mr. Lee has taken a harder line with North Korea than other recent South Korean presidents.
North Korea also announced it would block road traffic to a joint industrial estate across the heavily armed border if South Korea resumes propaganda broadcasts to the North.
South Korea said Monday it is implementing its own sanctions against the North in retaliation for the torpedo attack.
Some information for this report was provided by AFP, AP and Reuters.