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An international security expert believes Turkish President Erdogan may have overplayed his hand in the ongoing conflict in Syria.
It was the Russian and Turkish presidents' first meeting since at least 33 Turkish soldiers were killed in an airstrike near Idlib, sparking a NATO crisis.
The warning came after 33 Turkish soldiers were killed by airstrikes in northern Idlib province on Thursday. Turkey has blamed Russia.
Turkish action in Syria is just one part of a chain reaction that experts believe could lead to another humanitarian crisis in Europe.
The mayor of Bolu said he would arrange the buses for "whatever the number [of refugees]" who needed the service and wanted to travel on to Europe.
This week in pictures: COVID-19 spreads in Europe, Syrians flee violence and Greek protests
Turkey says it will not back down in a stand-off with Russia over the northern Syrian region of Idlib.
More than 900,000 people have been displaced by violence in northwest Syria in fewer than three months.
Turkish President Recep Tayyip Erdogan has announced he would hold a summit with his Russian, French and German counterparts on 5 March to discuss the situation in Idlib province, the last rebel stronghold in northwestern Syria.