HONOLULU — Senior Obama administration officials defended the White House’s policy to contain Iran’s nuclear weapons program Saturday night, arguing that the United States has built an international coalition whose sanctions have left the Iranians more politically isolated than ever.

In bilateral meetings with the leaders of China and Russia at an economic summit here on Saturday, Obama again stressed the importance of presenting a united front that “makes clear to Iran this is unacceptable,” said Ben Rhodes, a U.S. deputy national security adviser for strategic communications.

Rhodes added that Russian President Dmitry Medvedev and Chinese President Hu Jintao agreed that they would “remain committed to diplomatic efforts to compel Iran to live up to its international obligations.”

Obama’s stepped-up campaign comes in the wake of a report last week from the International Atomic Energy Agency that Iran may be proceeding with its nuclear weapons program. At a Republican presidential candidates debate Saturday night in South Carolina, several criticized Obama for not being forceful enough in his enforcement efforts on the Iranians.

Briefing reporters after the first day of the Asia Pacific Economic Cooperation summit, White House officials struck back at the GOP criticism, arguing that the international sanctions have ground Iran’s economy “to a halt.”

Rhodes said the United States would “not take any option off the table” in its campaign to prevent Iran from acquiring nuclear weapons.

Mitt Romney said during the debate that he would consider military action against Iran. After being read that statement by a reporter, Rhodes said: “I don’t think you solve serious foreign policy challenges through rhetoric alone; you do it through action.”

Rhodes cited the killing of al-Qaeda leader Osama bin Laden in May and the winding down of the Iraq war as national security achievements by the White House.

“This president has not hesitated to take any action to protect the United States,” he said. “His record of action sends a clear message this president is committed to our national security.”

View Photo Gallery: As the Asia-Pacific Economic Cooperation summit gets underway in Hono­lulu, President Obama and Chinese President Hu Jintao plan a bilateral meeting.