US, British and French forces launched military air strikes on multiple government targets in Syria early on Saturday in response to a suspected chemical weapons attack that killed dozens of people last week.

The intervention is the biggest by Western powers against Syrian President Bashar al-Assad in the country’s seven-yearcivil war and pitted the US and its allies against Russia.

In a televised address from the White House, Trump said: “A short time ago, I ordered the United States Armed Forces to launch precision strikes on targets associated with the chemical weapons capabilities of Syrian dictator Bashar al-Assad.”

“These are not the actions of a man. They are crimes of a monster instead,” Trump said referring to Assad and his role in the chemical weapons attacks.

As he spoke, at least six loud explosions were heard in Damascus on Saturday and smoke was seen rising over the Syrian capital.

Syrian state TV said the army’s air defences shot down 13 missiles fired in a US-led attack in the Kiswah area south of the capital Damascus.

US Defence Secretary Jim Mattis and Marine General Joseph Dunford said three main chemical weapons facilities were targeted at 9 pm EST (1 am GMT) by missiles from both the sea and aircraft, which triggered Syrian air defences; a scientific research centre in Damascus, a chemical weapons storage facility west of Homs and a chemical weapons equipment storage and an important command post, also near Homs.