Syria's President Bashar al-Assad is not ready to step down yet to make way for a transition government, US Secretary of State John Kerry says.
"Obviously he is not ready at this point in time," Kerry said in an interview with Al-Arabiya on the sidelines of the World Economic Forum meeting in Davos.
Syria's government and opposition are holding peace talks in Geneva this week. Kerry said if an agreement was reached many countries had offered to send peacekeepers to Syria, but he made clear US troops would probably not be part of such an operation.
"If there is a peace agreement, there are many countries that have already offered to step up and be peacekeepers in the new Syria," Kerry said.
"I don't think anybody believes that American troops should be on the ground."
On Thursday (local time) UN envoy to Syria, Lakhdar Brahimi, met members of the opposition in Geneva to discuss the agenda for further discussions on Friday.
The talks remain fragile, with both sides threatening to pull out. The government says it will not discuss removing Assad, while the opposition says it will not stay unless Assad's removal is the basis for talks.
Kerry again insisted Assad had no place in Syria's future.
"This is a man who has committed war crimes and still somehow wants to claim legitimacy to be able to govern the country," Kerry said.
But he said there could be a place for officials from Assad's government in a transition government as long as they "do not have blood on their hands".
Kerry said there was a role for Iran in Syria as long as it endorsed a 2012 plan that establishes a transitional governing body in Syria.
Iran was invited to attend the peace conference in Montreux but the UN invitation was later withdrawn after it failed to support the 2012 agreement known as Geneva 1.
"What Iran needs to do is either show that it's more than words, that its actions are willing to join the international community, or it will be very difficult to have Iran be part of this," Kerry said.