In another post, he’s dropping notoriously inaccurate barrel bombs “filled with whatever will go boom” from an old, Soviet-era warplane.

Israeli warplanes have reportedly carried out hundreds of airstrikes across Syria, including on the capital, Damascus.

Russian warplanes have intensified strikes on rebel-held areas, Iran-backed militias have sent fighters to reinforce the government's defensive lines, and Iran has said it is ready to send additional forces to Syria if asked.

The US launched missiles at a Syrian Air Force base where the Pentagon said a warplane had taken off before dropping bombs filled with the nerve agent sarin on the rebel-held town of Khan Sheikhoun.

China is showcasing its latest warplanes and attack drones at the show, and top Russian official Sergei Shoigu is expected to attend.