The two men discussed "the military activity of NATO and Russia in Europe, reinforcing confidence and preventing incidents," the Russian defence ministry said in a statement.

They also exchanged views "on the situation in Syria, emphasising the importance of cooperation in the fight against international terrorism," it added.

NATO said the conversation "focused on issues related to military posture and exercises".

"This face-to-face meeting demonstrates a clear mutual interest to maintain the military lines of communication, to align with NATO's policy of dialogue and transparency," it added in a statement.

General Valery Gerasimov had already met Jon Dunford, Chairman of the US Joint Chiefs of Staff, in Baku in February 2016. The military men then pledged to "reinforce communication" between their armies.

The United States and Russia already use a line of military communication on their aerial operations in Syria to prevent incidents between the two countries.

Washington ended all military cooperation with Russia after Moscow annexed the Crimea peninsula from Ukraine in 2014, including ending joint exercises and visits of US ships to Russian ports.

Tensions between Russia and the US rose to new levels last week after a Washington-led strike against the Syrian regime which Moscow denounced as "aggression" against its ally.