"We urge the maximum number of armed opposition factions to express their support and readiness to participate in the cessation," Kirby said on Tuesday.
On Monday, Russia and the United States announced an agreement on cessation of hostilities between the Syrian government of President Bashar Assad and the armed opposition factions had been reached in accordance with the ISSG communique. The ceasefire will come into force on February 27.
"We believe this arrangement is an important opportunity to stop the violence, faciliate the delivery of humanitarian assistance, and help provide the space necessary for the political process to continue," Kirby said.
The State Department added that the United States continues to work towards ending the Syrian conflict through political transition.
Syria has been mired in civil war since 2011, with the country’s government fighting numerous opposition factions and jihadist groups.
