Upcoming peace talks on a political transition in Syria will test whether Syrian President Bashar al-Assad can negotiate in good faith, U.S. Secretary of State John Kerry said on Tuesday before a new round of negotiations in Geneva.

Assad has said he thinks the Geneva talks can produce a new Syrian government that includes opposition, independents and loyalists, but has rejected the idea of a transition authority.

But Syria’s opposition has consistently said it wants a halt in attacks on civilians and for the Geneva talks to result in a transitional governing body for Syria that does not include Assad.

“The key right now is whether Assad is capable of negotiating in good faith, and we have to put that to the test,” Kerry told Bloomberg Television in New York.