"Not that I am aware of," Davis said when asked if Russia has officially notified the United States about its presence in Afrin.
Earlier on Monday, the Syrian Kurdish YPG units spokesman Redur Xelil told Sputnik that the group reached an agreement on fighting terrorism which envisages Russian presence near the city of Afrin in northern Syria.
Davis noted that the Defense Department has seen reports that the Russian forces would train YPG elements.
"The Afrin Kurds, these are not people we have worked with before," the spokesperson added. "Our support is limited to those who are actively fighting ISIS [Daesh]."
Davis said the United States has been supporting the YPG forces east of the Euphrates.
Russian Defense Ministry denied reports on Monday of its alleged plans to deploy a new Russian military base in Afrin. However, the ministry said a branch of the Russian reconciliation center will be established near Afrin.