In a forceful, videotaped message circulated on social media on Sunday, Secretary of State John Kerry urged the rival factions in Syria not to squander the opportunity to engage in United Nations-mediated talks that began haltingly on Friday in Geneva aimed at crafting a political settlement to the conflict.
As Mr. Kerry signaled in his speech, and as American officials have argued all along, the longer the war in Syria, the more fertile the ground for the militant Islamic State group to thrive and spread across the region.
The Russian news agency Tass has reported that Mr. Kerry spoke with his Russian counterpart, Sergey V. Lavrov, on Saturday and that the two men agreed on the need to settle humanitarian issues in the initial phase of the talks.