Russia is racing to reinforce its troops in Syria by sea and air before talks between the Russian and Turkish leaders in Moscow on Thursday, flight data and shipping movements show.

The two presidents, Vladimir Putin and Tayyip Erdogan, agreed to meet after a surge in tensions between their countries over fighting in Syria’s Idlib province between Russian-backed Syrian government forces and rebels allied to Turkey.

The fighting has raised the prospect of a direct clash between their armies, which operate in close proximity on opposing sides, and Erdogan hopes the talks will yield a ceasefire in Idlib.