DOHA, Qatar -- U.S. officials sought to shore up support Sunday for a tougher stand against Iran's nuclear program by saying Tehran had left the world little choice and expressing renewed confidence that holdout China would come around to harsher U.N. penalties.
Even as the Obama administration intensifies its diplomacy, Iran is showing little sign of bending to the will of its critics. Past U.N. sanctions have had little effect. Some outside experts have detected what they believe are new slowdowns in Iran's nuclear advances, but the Islamic republic is thought to be headed toward having nuclear weapons capability in perhaps a few years.
President Barack Obama's senior military adviser called for more time for diplomatic pressure to work and said from Israel, which has hinted that it might attack if negotiations to contain Iran's nuclear ambitions failed, that such action could have "unintended consequences" throughout the Middle East.
While diplomatic patience has its limits, "we're not there yet," U.S. Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, said in Tel Aviv.
U.S. Secretary of State Hillary Rodham Clinton, on a quick visit to Persian Gulf allies Qatar and Saudi Arabia, said Iran has not lived up to its nuclear obligations and has rebuffed U.S. and international efforts to engage in serious talks. She said Iran has a right to nuclear power, but only if shown unequivocally it is to be used just for peaceful purposes.
While Iran insists it has no desire to get the bomb, Clinton said it appears otherwise.
"The evidence is accumulating that that is exactly what they are trying to do," she said during a question-and-answer session with her audience at the U.S.-Islamic World Forum, attended by officials and scholars from around the world. She also used pointed language in stressing that after months of failed efforts aimed at direct talks with Iran, tougher action is now required.
"It's time for Iran to be held to account for its activities," she said, alluding to penalties designed to squeeze Iran's economy.
In her speech, Clinton said the U.S. and others were working on "new measures" to try to persuade Iran to change its course.
She added: "I would like to figure out a way to handle it in as peaceful an approach as possible, and I certainly welcome any meaningful engagement, but we don't want to be engaging while they are building their bomb."
Obama has said that work to broaden economic sanctions in the U.N. Security Council is moving along quickly, but he hasn't given a specific timeline. China, one of five permanent members of the Security Council, has close economic ties to Iran and can block a resolution by itself.
"We have the support of everyone from Russia to Europe. And I believe we'll get the support of China to continue to impose sanctions on Iran to isolate them, to make it clear that in fact they cannot move forward," U.S. Vice President Joe Biden told NBC's "Meet the Press" from Canada, where he was attending the Olympics.
"We need to work on China a little bit more," added Obama's national security adviser, James Jones. "But China wants to be seen as a responsible global influence in this. On this issue, they can't, they cannot be nonsupportive," he told "Fox News Sunday."
Clinton struck a similar tone, saying in Doha that "the weight is maybe beginning to move" toward China supporting sanctions.
Clinton's stops in Qatar and in Saudi Arabia coincided with a string of diplomatic and military contacts in the Middle East, including Mullen's visits to both Egypt and Israel.
Her top three deputies -- James Steinberg, Jacob Lew and William Burns -- were expected in the region in coming days. So was Gen. David Petraeus, chief of U.S. Central Command with responsibility for U.S. military operations across the Middle East.
Their agenda is not focused exclusively on Iran. There also is an American push for closer cooperation in Yemen against al-Qaida, a move toward bolstering diplomatic relations with Syria and efforts to get Israeli-Palestinian peace negotiations back on track.
Clinton's trip follows closely on the Iranian president's claim that his country had produced its first batch of uranium enriched to a higher level. Mahmoud Ahmadinejad also insisted on Thursday that Iran had no intention of building nuclear weapons, yet would not be bullied by the West into curtailing its nuclear program -- a reference to new U.S. financial penalties imposed a day earlier.
Earlier Sunday, in Cairo, Mullen said after meeting with Egyptian President Hosni Mubarak that Iran was a key challenge to the security of the Middle East. He accused Tehran of spreading its radical influence in Lebanon, Gaza, Yemen and Iraq.
Saudi Arabia and Qatar, both situated across the Persian Gulf from Iran, are concerned about Iran's nuclear ambitions. They are seen by the Obama administration as an important part of a regional effort to persuade the Iranians that it is in their economic interest to give up their uranium enrichment program as called for in a series of U.N. resolutions that Iran has ignored.
Associated Press writer Josef Federman in Jerusalem contributed to this report.
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