The US, UK and France launched coordinated strikes against Syrian research, storage and military targets as President Donald Trump sought to "punish" his Syrian counterpart Bashar al-Assad for a suspected chemical attack that killed over 70 people, media reports said.

The strikes on Friday night was intended to show Western resolve in the face of what the leaders of the three nations called persistent violations of international law, reports The New York Times.

"I ordered the US ' title=' US '>US armed forces to launch precision strikes on targets associated with the chemical weapon capabilities of Syrian dictator Bashar al-Assad," Trump said from the White House Diplomatic Reception Room.

"The combined American, British and French response to these atrocities will integrate all instruments of our national power: military, economic and diplomatic," Trump said.

In his speech, Trump deemed the chemical attack in Douma as "Not the actions of a man... They are crimes of a monster instead."

Trump indicated the strikes would continue until the Syrian regime's use of chemical weapons ends, reports CNN.

"We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents," he added.

The strikes targeted three facilities associated with Syria's chemical weapons arsenal, including a scientific research facility around Damascus, a chemical weapons storage facility around Homs alleged to be used for sarin gas and a nearby command post, according to the Pentagon.

The Syrian Observatory said the Syrian Army's 4th Division and Republican Guard were among the targets.

US aircraft including B-1 bombers and ships were used in the attack, US ' title=' US '>US defence officials said.

Witnesses told CNN that they heard explosions in Damascus which began while Trump was making his address.

The capital city's residents woke to the sounds of multiple explosions shaking the city before the dawn call to prayer.

The city and the hills are surrounded by military facilities, and it appeared that these were among the first targets, reports The New York Times.

Syrian state television said government air defence systems were responding to "the American aggression" and aired video of missiles being fired into a dark night sky.

It was not clear if they hit anything. It reported that 13 missiles had been shot down by Syrian air defences near Al-Kiswa, a town south of Damascus.

The targets were chosen to minimise the risk of accidentally hitting Russian troops stationed in Syria, according to Gen. James F. Dunford Jr., the chairman of the Joint Chiefs of Staff.

Defence Secretary Jim Mattis told reporters at the Pentagon on Friday night that the strike was completed and was designed as a one-night operation.

"Right now this is a one-time shot and I believe it has sent a very strong message to dissuade him to deter him from doing it again," he said.

The strikes marked the second time that Trump has attacked Syria to punish the government after it was accused of using chemical weapons.

In April 2017, the US ' title=' US '>US fired 59 Tomahawk cruise missiles at a Syrian air base in retaliation to a chemical attack that killed over 100 people.

While France and Britain joined the US, Germany refused to take part, even though Chancellor Angela Merkel called the use of chemical weapons "unacceptable", The New York Times reported.

British Prime Minister Theresa May said Syria had left the allies no choice.

"This persistent pattern of behaviour must be stopped... Not just to protect innocent people in Syria from the horrific deaths and casualties caused by chemical weapons but also because we cannot allow the erosion of the international norm that prevents the use of these weapons," she said.