Russian President Vladimir Putin arrived in Istanbul's Atatürk Airport late Tuesday to attend Wednesday the inauguration of the TurkStream natural gas pipeline project, which will transmit Russian natural gas to Turkey and Europe under the Black Sea.

The Russian president will also hold bilateral talks with President Recep Tayyip Erdoğan. Several hot topics are expected to be on the agenda, including the situation in Libya and Turkey's plans to deploy its military to the north African nation to support the internationally-recognized government amid a brutal offensive by rival forces loyal to commander Gen. Khalifa Haftar, who is based in the country's east.

Another important subject will include the indiscriminate assault by the regime of Bashar Assad, Moscow's ally, on the northwestern Syrian province of Idlib. Civilians are continuing to flee to areas near the Turkish border amidst further attacks. In September 2018, Turkey and Russia agreed to turn Idlib into a de-escalation zone in which acts of aggression would be expressly prohibited. Since then, over 1,300 civilians have been killed in attacks by the regime and Russian forces in the de-escalation zone as the cease-fire is persistently violated.

"We stand by Turkey's efforts to stop this senseless violence [in Idlib]. Putin should listen to Erdoğan in their meeting on January 8 to end the violence now," the U.S. Embassy in Syria tweeted minutes before Putin's arrival in Istanbul.

The visit also comes amid heightened tensions in the Middle East after a U.S. airstrike killed Iranian Gen. Qassem Soleimani near Baghdad's airport last week.

Earlier Tuesday, Putin made a surprise visit to Damascus for talks with Assad.