The US has carried out a missile attack against an air base in Syria in response to a suspected chemical weapons attack on a rebel-held town.

The Pentagon said 59 Tomahawk cruise missiles were fired at 04:40 Syrian time (01:40 GMT) from destroyers in the eastern Mediterranean, according to the BBC.

In a televised address, President Donald Trump reportedly said the base was the launch point for the chemical attack.

The BBC says he called on “all civilized nations” to help end the conflict in Syria.

Dozens of civilians, including many children, died in the suspected nerve gas attack on Tuesday in the town of Khan Sheikhoun in Idlib province. 

Pentagon has avoided hitting Russian forces during missile strike on Syria

Pentagon also said that United States did not target the sections of the airbase where Russian forces were believed to be present, according to Russia’s Sputnik news agency.

Speaking from his Mar-a-Lago estate in Florida, Mr. Trump branded Syrian President Bashar al-Assad a “dictator” who had “launched a horrible chemical weapons attack on innocent civilians.”

According to CNN, Mr. Trump said he had acted in America's “vital national security interest” to prevent the use of chemical weapons.

CNN says Trump's decision marked a dramatic shift in his position on whether the US should take military action against the Syrian President's regime -- which Trump opposed during his campaign for president -- and came after the President was visibly and publicly moved by the images of this week's chemical weapons attack.

The UK government called the strike “an appropriate response to the barbaric chemical weapons attack.”

The Pentagon said the Russian military, which is supporting the Syrian government, had been informed ahead of the US attack.

In a statement it said missiles fired from Navy destroyers USS Porter and USS Ross had targeted aircraft, aircraft shelters, storage areas, ammunition supply bunkers, air defense systems, and radars at Shayrat airfield in western Homs province.

The Pentagon added that the strike was intended “to deter the regime from using chemical weapons again.”

It did not give details of damage or casualties but the governor of Homs province said there had been deaths and parts of the base were on fire.

“It will take some time to determine the extent of the damage,” Talal Barazi told AFP news agency.