On the eve of high-level political and economic talks between the U.S. and China, a senior U.S. official says the two superpowers are still at odds over how to deal with North Korea and the details of U.N. sanctions to impose against Iran for its controversial nuclear activities.
The March 26 torpedo attack on the South Korean naval ship Cheonan killed 46 sailors and has further raised tensions on an already tense Korean peninsula.
An international investigation has blamed the North for the attack, a charge it denies.
On Monday, South Korean President Lee Myung-bak will address his nation about the incident to outline measures Seoul will take against Pyongyang, including among other possible steps, taking it to the U.N. Security Council where it could be further sanctioned.
China, North Korea's main patron, has been reluctant to publicly blame Pyongyang for the attack. But U.S. officials in Beijing for political and economic talks expect to intensively raise the issue with their Chinese counterparts this week.
A senior U.S. official, speaking to reporters on condition of anonymity, said the Obama administration "wants China to take some steps in the international arena to underscore" how serious the attack was.
While the official said it is not unusual for China to move very carefully on matters involving North Korea, it is important the U.S. shares its concerns and explains its position. He said the United States has been in close coordination with Seoul and would back all steps President Lee announces.
The official said China is still studying and digesting the implications of the investigation.
Also on the agenda at the Strategic and Economic Dialogue this week, Iran's suspect nuclear program.
U.S. Secretary of State Hillary Clinton is leading the U.S. delegation of nearly 200 officials to the talks.
China has strong economic and trade ties with Tehran and has been reluctant to support new sanctions against the Islamic republic. But Beijing recently agreed to support a U.S.-drafted sanctions resolution at the United Nations.
The U.S. official complemented China for progress on the Iranian issue and said some substantial steps are still required to assure a positive outcome in a U.N. Security Council vote.