The Kremlin issued a statement in Russian saying he had, in a telephone call with his Turkish counterpart, "expressed condolences over a tragic incident which resulted in the deaths of several Turkish troops in the al-Bab area".
Turkish police detained four Islamic State group suspects who were allegedly planning to carry out a "sensational" attack in Turkey and seized 24 suicide attack belts, officials said Thursday. Under the pretext of fighting the "Islamic State" the Turkish forces mainly attack Syrian Kurds.
A rebel commander told Reuters news agency that fighters from a pro-Turkish division of the Free Syrian Army were moving forward on Thursday from territory they had taken the day before.
Syrian government troops and allied militias, as well Turkish troops, the U.S-led worldwide coalition, and Russian Federation have been going after IS in different parts of the country.
Turkey is part of the US -led coalition against the militant group.
The Syrian army and allied fighters have become less than three kilometers from al-Bab, said the report.
Turkish-backed Syrian rebels have pushed into the ISIS-held city of al-Bab in northern Syria, BBC News reported.
Separate operations by Turkey and Mr Al Assad's forces, backed by Moscow, have trapped the extremists inside Al Bab which has been besieged since Monday when Syrian forces cut off a road leading into the town.
"The al-Bab operation must be completed immediately in the period ahead".
"They will need additional fighters to be in Raqqa as the Kurdish-led forces are advancing very rapidly from the north and west", analyst al-Hendi said.
The military said the incident occurred at around 8:40 a.m.in the region where the Euphrates Shield Operation has been continuing.
The two Russian pilots were forced to eject into terrorist-held areas, with the captain being killed by militant fire as he was descending.