Iran has informed the International Atomic Energy Agency (IAEA) – the UN's nuclear watchdog – in a letter that it is building a second uranium enrichment plant.
At the G20 Pittsburgh summit, the US, France and the UK will accuse Tehran of building a secret nuclear weapons capability and threaten further UN sanctions. This will ratchet up tensions and trigger renewed speculation that Israel might launch a pre-emptive strike.
So far, US-led efforts to increase pressure on Iran have failed in large part because of Russia's hostile stance in the UN security council. During Vladimir Putin's presidency (2000-08), Russia repeatedly opposed more punitive measures against Iran. Fuelled by a combination of anti-Americanism and renewed geopolitical ambition, Moscow insisted that Tehran had a sovereign right to build nuclear power stations – with Russian technological support.
But now that the Obama administration is moving its anti-ballistic missile shield from land-based installations in eastern Europe to mobile vehicles closer to Iran, the Russian president, Dmitry Medvedev, declared on Wednesday at the UN in New York that "sanctions are seldom productive but they are sometimes inevitable".
With the "reset" of US-Russian relations, the Kremlin has performed a spectacular "rethink" of its Iran policy. The "secret" Moscow visit by Binyamin Netanyahu on 7 September seemed to reassure the Russian leadership that Israel would not launch unilateral pre-emptive strikes against suspected Iranian nuclear installations – on the condition that Moscow promise not to equip Iran with the advanced S-300 system, an offensive missile capability that could deliver nuclear warheads.
If Russia drops its opposition to further sanctions, China is likely to agree or at least to abstain because Beijing's policy is to avoid isolation within the UN security council – except to block international interference in Chinese interests in Sudan or foreign meddling in "internal" issues such as Taiwan and Tibet.
Critics will be correct to argue that more UN sanctions against Tehran's nuclear activities are hypocritical, as they would perpetuate the inequality between non-nuclear states deemed too dangerous to have the bomb and nuclear states that are "not all stable or democratic", as Simon Jenkins has rightly remarked. Even Obama's US has not heeded President Hu's call for all nuclear-weapon countries to adopt China's "no first use" policy, providing Iran and North Korea with reasons to fear a US pre-emptive strike. Tehran and Pyongyang won't so quickly forget the fate of Iraq.
That's why so much depends on American and Russian commitments to reduce and eventually abandon their nuclear arsenals.
US-led punitive measures also tend to be counter-productive, as they turn countries into pariah states and embolden repressive regimes. Here Russia has a key role to play. Moscow is better placed than the west to help Iran develop its domestic economy by modernising the oil and gas sectors.
Without renewed Russian investment in Iran's largely obsolete energy industry, the oil-funded Mullah theocracy will struggle to hold on to power in the face of growing resistance – especially since the fraudulent re-election of President Ahmadinejad.
Together with Qatar, Russia and Iran (who together account for more than 60% of global natural gas reserves) are establishing a "gas troika" focusing on liquefied natural gas (LNG) that could lead to the biggest state-sponsored joint venture in the global energy market.
Along with new supply routes to emerging markets in Asia, LNG could produce a decoupling of the gas and oil price. With the oil price set to fall again once the current commodity bubble bursts (which it will when expansionary measures like "quantitative easing" are scaled back), the gas price would not be adversely affected, making investment in the gas sector more lucrative yet.
Moreover, the nascent global recovery, especially in China and other Asian countries, will increase demand for cleaner energy like natural gas. That is why the proposed "gas troika" is building a new pipeline system linking Iran to Qatar and ultimately to Asia. The plan is to pump gas from Iran's South Pars deposit, the world's largest with estimated reserves of about 14 trillion cubic metres, via a pipeline on the Persian Gulf floor to a LNG plant in Qatar's Ras Laffan province (about 100 miles from the deposit).
Qatar has signed a contract with China to supply 7m metric tons of LNG per year. South Korea's rapidly increasing consumption of liquefied gas creates another significant source of demand for gas produced by the troika, estimated to be worth $4bn.
Involving Qatar, which hosts a major US military basis, has the additional advantage of easing tensions between Iran and the Gulf states, which are increasingly nervous about Tehran's hardline stance. On this key issue and on the Israel-Palestine peace process, the Kremlin has now the unique chance to act as an honest broker.
In short, Moscow can combine the stick of economic and political sanctions against the ruling regime with the carrot of technological and financial support for developing Iran's energy sector. None of this will guarantee Tehran's compliance with international demands to disclose all its nuclear-related activities. But Russian leverage can make an important difference in defusing the growing tensions that threaten the entire Middle East.
Adrian Pabst, a lecturer in politics in the University of Kent at Canterbury.