US Defense Secretary James Mattis said that the airstrikes on targets in Syria were a "one-time shot" to send a strong message to Syrian President Bashar al-Assad. But he is not ruling out further attacks.

Mattis made the remarks at a briefing from the Pentagon Friday night, an hour after US President Donald Trump announced that the US and its allies France and Britain launched military strikes on Syria.

Actions by the United States and its allies in Syria would entail consequences for which they would have to bear responsibility, Russia’s ambassador in Washington Anatoly Antonov said in a statement.

"We have warned that such actions will not remain without consequences. All responsibility for them rests upon Washington, London and Paris," he said. "The United States, a country that has the largest arsenal of chemical weapons, has no moral right to accuse other countries."