The US is seeking military talks with Russia on Syria, and hopes they could take place "very shortly", Secretary of State John Kerryhas said.
The US has been concerned about Russia's increased military presence in Syria.
"We're looking for ways in which to find a common ground," said Mr Kerry.
Moscow has meanwhile said that any request from Syria to send troops would be "discussed and considered".
"But it is difficult to talk about this hypothetically," Kremlin spokesman Dmitry Peskov added.
Arriving in London for talks with the UAE, Mr Kerry told reporters: "The president believes that military-to-military conversation is an important next step and hopefully will take place very shortly."
Russia's foreign ministry offered such talks earlier in this week.
A spokeswoman said on Friday: "We have never refused dialogue with the United States. (We) are open to it now on all matters of mutual interest, including Syria," according to Reuters.
Russia - Syria's ally in the four-year civil war - says it is helping Syria fight Islamic State militants.
Moscow has increased its presence in the country just as the regime is losing ground to rebel groups.