Last Friday's Tomahawk missile strike by the US on Syria's Shayrat airfield destroyed "20 percent of Syria's operational aircraft", US defence secretary Jim Mattis has said, according to a press statement released by the Pentagon.

The strike, which was a response to a chemical weapon attack last Tuesday in Khan Sheikhoun in Syria, believed to have been launched by the Syrian government of Bashar al-Assad, also resulted in the damage or destruction of fuel and ammunition sites and air defence capabilities at the airfield, Mattis said yesterday.

The Syrian government has lost the ability to refuel or rearm aircraft at Shayrat, he added.

Mattis said that the airstrike was launched by the US to deter future use of chemical weapons in the country.

The Syrian government "would be ill-advised" to use chemical weapons ever again, Mattis added.

- dpa