WASHINGTON – Iran is welcome to join discussions over the future of Syria along with international powers, the Obama administration said Tuesday.The new US position is a reversal from a previous line out of the State Department that rejected any Iranian role in the talks so long as the country continued its support for Syria’s embattled president, Bashar Assad, and refused to accept progress in previous rounds of talks held in 2013 and 2014 in Geneva.Those talks produced a communiqué, which amounts to a rudimentary path out of the bloody four-year conflict: A political transition, ultimately toward a Syrian unity government. The US and its European allies still believe Assad must ultimately leave the presidency in order for the war to end.For years, the White House considered Iran and Russia – both staunch allies of Assad – as obstacles to that end. But, at the UN General Assembly in New York last month, President Barack Obama said he would be willing to engage with both countries to secure a realistic end to the conflict.State Department spokesman John Kirby confirmed the change in policy on Tuesday, saying a “multilateral” invitation to Iran would not be opposed by the United States.A formal invitation has yet to be received in Tehran, Iranian officials told local media outlets. And whether they will accept is an open question: Just weeks ago, Iran’s supreme leader, Ayatollah Ali Khamenei, ruled out any future negotiations with the US after successfully brokering a nuclear agreement together in July.Moscow and Tehran consider Assad the legitimate president of Syria, which, under his leadership, has seen more than a third of its countrymen displaced and nearly 300,000 killed.Iran and Russia have deployed forces on the ground to aid Assad. They are nominally targeting Islamic State, based in Syria’s east, but are also striking Western-backed Syrian rebels primarily motivated to remove Assad.In January 2014, before the second round of negotiations in Geneva, the US insisted that UN Secretary-General Ban Ki-moon disinvite Iran from the negotiations over their refusal to endorse the Geneva communiqué. Since then, both Russia and Iran have stepped up their efforts in the war.The US, on the other hand, has ended its train-and-equip program of moderate Syrian rebels. The Pentagon said it struggled to find fighters who were willing to exclusively battle Islamic State, and not Assad.Complicating Iran’s role, Sunni powers opposed to Assad – including Saudi Arabia and the Gulf states – have refused to participate in any talks to which Tehran is a party. They also say they will refuse any resolution to the conflict that allows Assad to stay in power.Talks are set to resume in Vienna at the end of the week.