WASHINGTON // President Barack Obama's reluctance to give military aid to Syrian rebels may be explained in part in three words: Iranian nuclear weapons.
For the first time in years, the United States has seen a glimmer of hope in persuading Iran to curb its nuclear enrichment programme. Negotiations resume this week in Almaty, Kazakhstan, where encouraging talks in February between six world powers and the Islamic Republic ended in what Iranian diplomat Saeed Jalili called a "turning point" after multiple thwarted steps toward a breakthrough.
But Tehran is unlikely to bend to Washington's will on its nuclear programme if it is fighting US-supplied rebels at the same time in Syria. Tehran is Syrian President Bashar Al Assad's chief backer in the two-year civil war that, by UN estimates, has left at least 70,000 people dead.
Russia also is supplying Mr Al Assad's forces with arms. And the US does not want to risk alienating Russia, one of the six negotiating nations also seeking to limit Iran's nuclear programme, by entering what would amount to a proxy war in Syria.
The White House has at least for now put the nuclear negotiations ahead of intervening in Syria, according to experts.
"I think that the United States has not taken a more active role in Syria from the beginning because they didn't want to disturb the possibility, to give them space, to negotiate with Iran," Javier Solana, the former European Union foreign policy chief, said at a Brookings Institution discussion about this week's talks. Mr Solana, who was a top negotiator with Tehran in the nuclear programme until 2009, added: "With Russia, we need to be much more engaged to resolve the Syrian problem and, at the end, the question of Tehran."
Adding to the mix is the unpredictable relationship between the US and China, which has been leery of harsh western sanctions on Iran and is expected to follow Russia's lead on the nuclear negotiations. Without Russia and China's support, experts say, the West will have little success in reaching a compromise with Iran.
"Resolving the nuclear impasse with Iran is the biggest challenge this year in the Middle East, and that requires careful handling of not only Iran, but Russia and China," said retired Ambassador James F Jeffrey.
But few expect any major breakthroughs in the negotiations beginning this week until after Iran's presidential election in June.
Mr Al Assad's fall would strip Iran of its closest ally in the Middle East and perhaps spur the Islamic Republic to aggressively pursue a nuclear weapon as it faces further isolation. At the same time, it could encourage Tehran to make some modest concessions.
"You can argue it either way, but in the end I think the collapse of Assad makes a nuclear deal more likely," Gary Samore, of the Kennedy School of Government at Harvard University, said on Monday.
