US President Donald Trump has warned Russia and Iran about their association with the head of the Syrian regime, Bashar Assad, as he announced the launch of retaliatory strikes after an apparent chemical weapons attack last week. In a primetime address from the White House on Friday, Trump said: "To Iran and to Russia, I ask: What kind of a nation wants to be associated with the mass murder of innocent men, women and children?" Trump called the two countries those "most responsible for supporting, equipping and financing the criminal Assad regime." "The nations of the world can be judged by the friends they keep,” he said. Trump stressed he is "prepared to sustain" strikes against Syria until the use of chemical agents stops. The response launched by the US, along with France and the United Kingdom, against the Syrian regime came days after Assad’s alleged use of chemical weapons on its citizens in the rebel-held Damascus suburb of Douma. Assad deployed chemical weapons in what was a "significant escalation in a pattern of chemical weapons use by that very terrible regime," said Trump.