An upcoming meeting by the P5+1 on trying to curb Iran's nuclear program has been postponed at China's behest, senior officials from three of the countries involved said Monday. One of the officials said China cited scheduling problems in asking for the deferral, and the six countries may instead talk by videoconference before the year's end. A US spokesman said that the meeting might take place next year. The official said China seemed to have genuine problems in attending the meeting in Brussels or outside the Copenhagen climate summit and did not appear to be seeking to delay it. Still, the development was a setback in efforts to present a unified front on Iran in the face of continued Iranian defiance on its nuclear program. Because it relies on Teheran for gas and oil, China is the weakest link in international attempts to punish Iran for defying a UN Security Council demand that it stop enriching uranium, a process that can lead to the production of both nuclear fuel and the fissile core of warheads. Meanwhile on Monday, Defense Minister Ehud Barak urged the world to agree to tough new sanctions on Iran, suggesting that military strikes remained a final option should Teheran refuse to heed UN Security Council demands to curb its nuclear activities. The comments were made during an official visit in Austria. Barak indicated Israel was prepared to wait for an unspecified period of time to give more for diplomacy in trying to end Iran's nuclear defiance. "We still believe that its time for diplomacy, tough diplomacy," Barak told reporters. "There is a need for tough sanctions ... something that is well and coherently coordinated to include the Americans, the EU, the Chinese, the Russians, the Indians." At the same time, he said, "we recommend to all players not to remove any options from the table," just as "we do not remove it." Both Israel and the US have said all options - diplomatic language for military strikes - remain open in attempts to strip Iran of the capability of turning what it says are peaceful nuclear activities into a program geared toward making nuclear arms. Also speaking on the issue of sanctions was US Secretary of State Hillary Rodham Clinton, who said earlier on Monday that US President Barack Obama's nearly yearlong effort to engage Iran has fallen short. New sanctions are needed, she said, to press the leadership in Teheran to provide more information about its alleged nuclear program. Clinton's pessimistic remarks come as an end-of-year deadline, set by the Obama administration, looms for the Iranians to prove that their nuclear intentions are peaceful. She said the administration has offered Iran a chance to participate in meaningful discussions about its nuclear activities and intentions or face fresh penalties for defiance in line with the dual-track, carrot-and-stick approach. That dual effort, though, has "produced very little," she said, adding that "additional pressure is going to be called for" to get results. "I don't think anyone can doubt that our outreach has produced very little in terms of any kind of a positive response from the Iranians," Clinton told reporters at a joint State Department news conference with visiting Spanish Foreign Minister Miguel Moratinos. Clinton's remarks also came as the House of Representatives prepares to vote Tuesday on legislation that would give the administration authority to punish foreign individuals and companies that sell or ship gasoline to Iran. The bill, known as the Iran Refined Petroleum Sanctions Act, is expected to pass easily. Similar legislation is under consideration by the Senate but is unlikely to be adopted before January, in part because the administration has asked for some revisions in language. Administration officials also want to see lawmakers deal first with health care reform, according to congressional aides. "The second track of our dual-track strategy is to bring the international community together, to stand in a united front against the Iranians and try to impress upon them the importance of changing their actions and decisions concerning their nuclear program," Clinton said. "Certainly, additional pressure is going to be called for in order to do that." As Obama's deadline nears, the administration is also preparing to press the United Nations, individual countries and blocs of nations, such as the EU, to adopt a range of new sanctions on Iran early next year. Iran is already under three sets of penalties from the UN Security Council, as well as unilateral sanctions from numerous states. The administration's suggested package of sanctions includes travel restrictions and asset freezes on specific Iranian individuals and entities along with measures that would target the trade and commerce, insurance and reinsurance, banking, energy and shipping sectors, according to officials familiar with it. The push toward new sanctions has picked up steam in recent weeks as Iran has bolstered its defiance of attempts to get it to prove its nuclear program is civilian, as it claims, and not a covert attempt to develop atomic weapons as the US and its allies believe. Clinton noted each these developments in her comments on Monday and said they "should raise deep concern among all people." Jpost.com staff contributed to this report.