United Nations envoy Kofi Annan says Iran must be part of the solution in Syria.

Mr. Annan held talks in Tehran Tuesday with Iranian Foreign Minister Ali Akbar Salehi as part of Mr. Annan's efforts to rescue his moribund peace plan for Syria.

Mr. Annan said his presence in Tehran proves Iran has a positive role to play in Syria. Iran is Syria's biggest regional ally and has supplied military equipment to the government of Syrian President Bashar al-Assad.

White House spokesman Jay Carney said Tuesday no one with a straight face could argue Iran has had a positive impact on Syria.

Mr. Annan met with President Assad in Damascus Monday. The U.N. envoy said Mr. Assad proposes containing the fighting in the extremely violent districts and then spreading out across the country from there. Mr. Annan later traveled to Baghdad to discuss the Syrian crisis with Iraqi Prime Minister Nouri al-Maliki.

Carney said he is highly skeptical that Mr. Assad is willing to meet his commitments. Carney also said the Syrian leader will go down in history as a brutal tyrant who murdered his own people.