The United States says it expects Iran to be invited for the first time to multilateral talks with the United States and Russia over the Syrian conflict.
"It’s up to Iran to decide whether they’re going to or not when they are asked,” State Department spokesman John Kirby said on October 27.
"It's important for us that key partners are in these discussions,” he added. "Iran could be “a key partner, but they are not now."
Envoys from the United States, Russia, as well as Arab and European countries are to attend the talks starting in Vienna on October 29.
Syria's Western-backed opposition and the United States’ Gulf Arab allies oppose Iran's role in the Syrian war.
Tehran has been a main backer of Syrian President Bashar al-Assad, providing military advisers and subsidized weapons to prop up his government.