Russian President Vladimir Putin attends a meeting with his Syrian counterpart Bashar al-Assad in Damascus, Syria January 7, 2020. Putin met Assad in Damascus on Tuesday, the Russian leader's second trip to Syria since Moscow intervened decisively on the Syrian president's behalf in the country's civil war. Sputnik/Alexei Druzhinin/Kremlin via REUTERS

Russian President Vladimir Putin, Defence Minister Sergei Shoigu and Syrian President Bashar al-Assad attend a meeting in Damascus, Syria January 7, 2020. The visit comes at a time of heightened regional tension - Assad's other main military ally, Iran, has said it will retaliate against the United States for the killing of an Iranian general in a drone strike. Qassem Soleimani, who was one of the key figures in Syria's war as the architect of Iranian military operations in the Middle East, had just arrived in Iraq from Syria when he was killed by a U.S. drone on Friday at Baghdad airport. Sputnik/Alexei Druzhinin/Kremlin via REUTERS

Russian President Vladimir Putin, Defence Minister Sergei Shoigu and Syrian President Bashar al-Assad attend a meeting in Damascus, Syria January 7, 2020. Russian and Iranian support has helped Assad win back nearly all the territory lost to rebels who tried to overthrow him during the civil war that began nearly nine years ago. Sputnik/Alexei Druzhinin/Kremlin via REUTERS

Russian President Vladimir Putin, Defence Minister Sergei Shoigu and Syrian President Bashar al-Assad attend a meeting in Damascus, Syria January 7, 2020. Syrian state news agency SANA showed a photograph of Putin smiling as he shook Assad's hand and said they had listened to a military presentation by the head of Russian forces in Syria. Sputnik/Alexei Druzhinin/Kremlin via REUTERS

Russian President Vladimir Putin, Defence Minister Sergei Shoigu and Syrian President Bashar al-Assad attend a meeting in Damascus, Syria January 7, 2020. Putin and Assad discussed recent developments in the region and plans to "eliminate terrorism" in the Idlib region, one of the last pieces of Syrian territory held by anti-Assad insurgents, SANA reported. Sputnik/Alexei Druzhinin/Kremlin via REUTERS

Russian President Vladimir Putin, Defence Minister Sergei Shoigu and Syrian President Bashar al-Assad attend a meeting in Damascus, Syria January 7, 2020. Putin met Assad in Damascus on Tuesday, the Russian leader's second trip to Syria since Moscow intervened decisively on the Syrian president's behalf in the country's civil war. Sputnik/Alexei Druzhinin/Kremlin via REUTERS