A group meant to enforce a nascent halt to hostilities in Syria has yet to meet, the State Department acknowledged Tuesday.
"My understanding is they have yet to meet," spokesman Mark Toner told reporters.
"Our team obviously is working to get this group together and start it on its work as soon as we can. But we don't have anything new to announce in terms of this group actually meeting."
They are likely to meet tomorrow, Toner added.
The UN task force is meant to enforce a cessation of hostilities that is set to go into effect by week's end. Toner was unsure that the cessation of hostilities would go into effect by Thursday, "but certainly we're going to expect that there is progress," he said.
He added that Russia, a key backer of Syria's Bashar al-Assad, should "put up or shut up" if Moscow is serious about ending the Syrian bloodshed.
"They need to exert influence on the Syrian regime to make sure that happens," he said.
The tenuous pause in violence is part of a deal brokered last week in Munich by world and regional powers that also seeks to expand humanitarian access to besieged areas in the country.
Some aid deliveries have begun, Toner said. But he could not specify which cities have seen relief.
After meeting with Syrian Foreign Minister Walid Muallem in Damascus, the UN's Syria envoy, Staffan de Mistura, said it is the duty of the government to allow aid into besieged areas.
"Tomorrow we test this and we will be able to talk more about it," he said.
Under the internationally-brokered agreement the besieged towns of Deir ez-Zour, Kafrayah and Fouah are to be allowed simultaneous air delivery of aid this week, while areas of rural Damascus, Madaya, Mouadhimiyeh, and Kafr Batna will have land deliveries that will "continue as long as humanitarian needs persist".