Some of the world's leading nations met in China on Wednesday to discuss ways to persuade Tehran to abandon its nuclear program and help diffuse the escalating tension in a region torn by turmoil and conflict.

The closed-door meetings in a Shanghai hotel by deputy ministers of the U.N. Security Council's five permanent members – the United States, Russia, China, Britain and France – plus Germany and the European Union, revolved around a negotiated solution to the nuclear standoff between Iran and the West.

Diplomats say the proposals under discussion included carrot-and-stick options, such as knocking up a new set of international sanctions on Iran, which has consistently rejected Western fears that its nuclear program was intended to build atomic weapons.

While the representatives were unable to come up with an agenda for negotiations with Iran, they agreed to continue working on a proposal on "how to conduct dialogue and negotiations with Iran," according to China's assistant foreign minister He Yafei.

He did not say when they hoped to resume negotiations with Tehran, but stressed the agenda "should lay out a comprehensive, durable and proper solution," which reportedly includes new political, economic and security incentives to lure Iran into negotiations.

China is seeking to replicate the six-way talks over North Korea's nuclear program, hoping that U.S. discussions with Iran over Iraq could bring Washington and Tehran together to discuss the nuclear standoff. Unconfirmed reports said such talks between the two sides were already taking place secretly.

The Shanghai talks came a week after Tehran announced it was operating 492 new centrifuges at the Natanz uranium enrichment plant, in violation of U.N. resolutions to freeze the process.

Iran's determination to proceed with its program, and unmoved by three sets of U.N. economic sanctions, suggest that more international pressure would do little to push Iran to abandon the program that it insists is solely for peaceful energy purposes and the country's progress.

But while U.S. officials have toned down threats of a military confrontation with Iran, Israel has been preparing to defend itself against an attack from the Islamic republic, whose repeated threats to wipe it out has shaken the Jewish state.

The U.S. chairman of the joint chiefs of staff, Admiral Michael Mullen, said Tuesday that although he expected Iran to pose the top challenge for the United States over the next three to five years, he hoped for dialogue in the future.

Mullen told the Heritage Foundation, a conservative American think tank, that while "all options" needed to be open in dealing with Tehran's nuclear program, "I am not arguing that this is where the next conflict occurs."

"And I would hope that in the future we could figure out a way to dialogue with them to figure out a way ahead," he added. "We've done that in the past with our enemies. We should be able to do that as well."

The U.S. administration of George W. Bush has so far refused to speak to Iran until it abandons uranium enrichment.

Middle East analysts suggest that the Bush administration has reconsidered a military strike against Iran or starting a new war in the region as its political term comes to a close in January 2009.

But Washington is not leaving its Israeli ally to face the Iranian threat alone, amid a recent escalation of words between Tel Aviv and Tehran, as if both sides were waiting for the other to strike first.

Israel's National Infrastructure Minister Binyamin Ben-Eliezer warned last week that an Iranian attack against his country "would lead to the destruction of the Iranian nation."

Iran's deputy commander of the army, Mohammad Reza Ashtiani, responded on Tuesday that his country would "eliminate Israel from the global arena" if attacked by the Jewish state.

U.S. national security adviser Stephen Hadley was in Israel on Wednesday discussing security cooperation with political and security leaders and U.S. support to confront a possible Iranian strike.

Hadley's visit came as Israel on Tuesday successfully tested a mock ballistic missile, the Blue Sparrow, simulating an Iranian attack after the latter boasted developing longer-range missiles that Israel thinks could ultimately be armed with nuclear warheads.

Little information was available on Hadley's discussions, but Israeli media speculated his visit was linked to connecting Israel to an American ballistic missile early warning system to warn of rocket attacks from Iran.

Arab commentators say that while international efforts are focused on Iran's nuclear program and the danger that may pose, insufficient attention was being given to Israel's own nuclear arsenal and the threat it has on regional security should a military confrontation erupt with a potentially nuclear Iran.

Israel, the only Middle Eastern country not to have signed the nuclear Non-Proliferation Treaty, has never admitted it had nuclear weapons, but is widely believed to have around 200 warheads.