The Russian Defence Ministry said on Friday that Syrian air defences would be beefed up after US cruise missiles struck an air base in western Syria, Russian news agencies reported.

The ministry was also cited as mocking the effectiveness of the US strikes as “extremely low” saying that 23 missiles had hit their targets but it was unclear where 36 others had landed.

Four Syrian military personnel had been killed in the strikes, two were missing, and six wounded, it said. Six Syrian military jets had also been destroyed.

Militants launched an offensive on Syrian government positions immediately after the strikes, the ministry was quoted as saying.