SHANGHAI — President Barack Obama, fresh from making progress in his efforts to get Russia on board for possible tough new sanctions against Iran, will attempt the even more difficult task of prodding China's leaders to get tough on Iran.

Making his first trip to China, Obama is set to begin three days of meetings to discuss climate change, North Korea and the global economic crisis with President Hu Jintao. But atop that list will be an effort to try to get Hu close to the spot where Russia, the other reluctant-to-sanction permanent member of the U.N. Security Council, appears to have arrived.

After an hourlong meeting in Singapore on Sunday afternoon, Obama managed to get President Dmitri A. Medvedev of Russia to express dissatisfaction with Iran's response to a nuclear offer made by world powers, raising the prospect that sanctions may be the next step in the West's continuing effort to rein in Tehran's nuclear ambitions.

The leaders, meeting on the sidelines of an Asia-Pacific summit meeting in Singapore, also made progress in efforts to negotiate a replacement for START, a key arms control treaty between the United States and Russia that expires in December, administration officials said.

On Iran, Obama and Medvedev discussed a timetable for imposing sanctions if Tehran and the West do not reach an accord soon on a proposal in which Iran would send its stockpile of enriched uranium out of the country for either temporary safekeeping or reprocessing into fuel rods, administration officials said.

More significantly, Medvedev also alluded to running out of patience. He said that while the negotiation with Iran was continuing, "we are not completely happy about its pace. If something does not work, there are other means to move the process further."

On Sunday, Obama became the first American president to meet with Myanmar's military leaders when he attended a summit meeting of the Southeast Asian group ASEAN.

After the talks, the group issued a joint statement that called for Myanmar's elections scheduled for next year to be free and fair. But the statement did not call for the release of Myanmar opposition leader Aung San Suu Kyi. White House officials said that Obama made a point of demanding her release when he made a speech to ASEAN members.