Iran's announcement to proceed with a more advanced uranium enrichment program has stepped up calls in the United States, Europe, and Israel for a new round of multilateral sanctions against Tehran. The West still faces a strenuous battle to win over China, which has insisted on the need for further negotiations aimed at persuading the Islamic Republic to place its nuclear program under greater international control. February could prove a pivotal month, with a hawkish France presiding over the Security Council and domestic pressure mounting on U.S. President Barack Obama to show results after a year of often frustrating diplomacy.

Here's a list of the key players who will be negotiating what Washington hopes will be the fourth round of U.N. sanctions against Iran:

Susan E. Rice
The United States' U.N. ambassador

Rice is the only U.N. ambassador who serves in her government's foreign-policy cabinet, placing her in a unique position to help shape her government's policy toward Iran. But this will mark her first major role as a negotiator on the Iranian nuclear crisis, pitting her against Russian and Chinese envoys who have traditionally resisted tough sanctions against Iran. Last year, Rice negotiated a similar sanctions resolution against North Korea, securing support from Pyongyang's powerful friends in Beijing. She has also ushered through a U.S.-sponsored resolution aimed at reducing the spread of nuclear weapons.

Rice will be looking to sanction Iran's central bank and press for targeted travel and financial restrictions against officials and businesses linked to Iran's Islamic Revolutionary Guard Corps, including a group of companies sanctioned Wednesday by the Treasury Department. But Rice will be under pressure to achieve a more ambitious outcome, particularly in light of Secretary of State Hillary Clinton's pledge to impose "crippling sanctions" on Iran.

"We are committed to working with other nations to address the very serious dangers posed by Iran's nuclear program and its failure to meet its international obligations," Rice told Turtle Bay. "We are pursuing a dual-track strategy of engagement and pressure. Iran's recent decision to enrich uranium to 20 percent, combined with the revelation of the secret Qom facility and other recent statements and actions, gives urgency to giving full meaning to the pressure track."

Gerard Araud
France's U.N. ambassador

France's former political director oversaw his government's Iran policy from 2006 until last year, and has played a central role in crafting the past three previous Iran sanctions resolutions. Now in New York,  Araud has been pushing a harder line than the Americans, advocating an expanded arms embargo and sanctions on Iran's oil revenues. He has extensive experience in the Middle East, and has served two stints in Israel, first as a low-level first secretary in the early 1980s, and later as France's ambassador in Tel Aviv. He is also said to believe that Israel would be willing to launch a military strike against Iran if sanctions fail to restrain Iran's nuclear ambitions.

Araud recognizes that any U.N. sanctions resolution that emerges from the council will be weak, but that it will provide political cover for tougher sanctions from the United States and Europe. "All our efforts to engage negotiations with the Islamic Republic of Iran, all our efforts have failed. Since 2003 we have tried to open a negotiation with Iran," Araud said recently. "And, as you know, President Obama has made a new proposal of engagement with Iran, we have made several very concrete proposals which would allow Iran to develop peaceful use of nuclear energy. Iran has never entered into a negotiation. Iran has not accepted our proposals. The clock is ticking. Iran is enriching uranium and we don't have any, any explanation for the use of this enriched uranium since Iran does not have a nuclear power plant."

Vitaly I. Churkin
Russia's U.N. ambassador

Churkin is a scrappy diplomatic negotiator, and a skillful public debater who once served as a foreign-policy spokesman for the Soviet Union and later the Russian Federation. Russia has been reluctant to impose tough sanctions on Iran for years. Diplomats say that Russia's defense establishment has argued that Iran's capacity to produce nuclear weapons has been overblown by the West and that the United States and Europe would do better to focus on negotiations with Tehran. But Moscow has grown alarmed at Iran's increasingly sophisticated ballistic missile program. Russian criticism of Tehran has sharpened since Iranian President Mahmoud Ahmadinejad last year rejected an offer to swap low-enriched uranium for fuel for an Iranian research reactor that produces medical isotopes. Russia would have been a principal supplier. The Iranian president said last week that he was now prepared to reconsider the offer, but a few days later he announced Iran would seek to enrich its own uranium to fuel the reactor. U.S. and European diplomats say they have received assurances from Moscow that it is now ready to pursue sanctions against Tehran. Still, Russia is always something of a wild card and the West can count on Churkin to at least try to water down any final resolution.

Sir Mark Lyall-Grant
Britain's U.N. ambassador

Like his French counterpart, Lyall-Grant has also served as his government's point man on Iran sanctions, acting as Britain's political director from early 2007 to October 2009. Lyall-Grant has grown deeply skeptical over what he sees as Iran's repeated pledges to pursue a negotiated settlement to the nuclear crisis. But he has played a fairly low-key role in public. "I think you can see there's clearly this pattern of violations of international obligations and an unwillingness of Iran to negotiate seriously with the international community over the nuclear issue," he said recently.

China: ?

All eyes are upon China. But nobody seems to know who to negotiate with on this issue. China's designated point man on Iran, He Yafei(right), is set to move to Geneva to serve as China's U.N. ambassador there, and has been a no-show at recent big-power pow-wows on Iran. Chinas U.N. ambassador in New York, Zhang Yesui, meanwhile, is headed to Washington sometime next month to serve as his country's ambassador to the United States. Li Baodong, who currently heads Beijing's embassy in Geneva, will become China's new U.N. ambassador. But it's not clear how soon he will be taking up the new post.

No matter who represents Beijing, the Chinese are expected to take a hard line. Given its growing commercial links to Iran, China is considered the toughest obstacle to painful sanctions. China has surpassed the European Union as Iran's chief trading partner, according to a recent analysis by the Financial Times that measured trade between Iran and China that appears on official records as originating in the United Arab Emirates.

What's more, the negotiations are playing out in a period in which tensions between the United States and China are high. Beijing is furious over the U.S. decision to sell arms to Taiwan and for President Obama to meet with the Dalai Lama. China's diplomats have expressed disappointment at what they see as Washington's lukewarm response to Ahmadinejad's latest offer to reconsider the uranium-fuel swap. "To talk about sanctions at the moment will complicate the situation and might stand in the way of finding a diplomatic solution," Chinese Foreign Minister Yang Jiechi said last week in Paris.

Sergei Lavrov
Russia's foreign minister

Lavrov casts a long shadow over deliberations in the U.N. Security Council. Having spent nearly a decade in New York as Russia's U.N. envoy, he has a deeper knowledge of the history of Security Council negotiations than many ambassadors sitting in New York (including Churkin, who takes orders from Lavrov). He also harbors a deep suspicion of the intentions of the United States, which based its legal case for its 2003 invasion of Iraq on Baghdad's purported violation of a 12-year-old cease fire resolution requiring Iraq's disarmament. Lavrov has insisted that every subsequent resolution involving U.N. sanctions against Iran or North Korea explicitly rule out any language that could be used as a pretext for future military action. Expect the same in any upcoming Iran resolution.

Benjamin Netanyahu
Israel's prime minister

The unspoken subplot of the discussions on Iran is whether Israel will launch a military strike against Iran's nuclear installations, as it did against Iraq in the 1980s, if it views the international effort to restrain Iran as too weak. Netanyahu reacted to Iran's announcement to advance its uranium enrichment activities by calling for immediate and "crippling" sanctions, "not moderate sanctions, or watered-down sanctions. Iran is racing forward to produce nuclear weapons." Netanyahu's envoy in New York is Gabriela Shalev, who is expected to try to discretely maintain pressure on Rice and her colleagues to pursue a tough line.

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