The Obama administration is pushing China and other key nations to enforce tough international sanctions against Iran and to enact their own penalties.

Senior U.S. officials said Thursday they would travel soon to China, Japan, South Korea and the United Arab Emirates to demand compliance with U.N. Security Council measures imposed on Iran over its suspect nuclear program. Those sanctions apply to Iranian institutions involved in its nuclear and missile development programs.

The campaign comes as the U.S. and its allies seek to pressure Iran into returning to talks aimed at halting its uranium enrichment program. They are also pressing Iranian leaders to prove the country's nuclear program is peaceful, as Tehran claims.

The officials said they would warn China in particular about new U.S., European, Canadian and Australian sanctions that can be used to punish foreign firms that do business with Iran's energy sector.

China has vast energy needs and has large investments in Iran, leading to concerns that Chinese companies may seek to move in as European companies pull out.

"We want China to recognize its responsibility not to backfill when responsible governments show restraint and distance themselves from Iran," said Robert Einhorn, the State Department's special adviser for nonproliferation and arms control.

"The Chinese will argue that they have important energy security needs, tremendous demands for energy and they need to do what's necessary to ensure energy security," he told a congressional committee.

He said Beijing must "recognize that as a permanent member of the Security Council it's their responsibility to prevent proliferation and to put pressure on Iran and to persuade Iran not to pursue nuclear weapons."

Einhorn will be going to China, Japan and South Korea beginning next week with Daniel Glaser, deputy assistant Treasury secretary for terrorist financing and financial crimes. Both testified Thursday before the House Committee on Oversight and Government Reform on the effect of the sanctions on Iran.

Glaser said the key to the effectiveness of the sanctions was getting other countries on board. He cited Asia, the Middle East and South America as the three regions of the world where the most work was needed.

"The challenge is to make these sanctions as broad as possible, and what I mean by that is global implementation," he said. Glaser said that Stuart Levey, the Treasury's point man on sanctions, would be traveling to the United Arab Emirates in August to discuss the importance of the penalties with officials there.