The US missile strike on Syria "targeted aircraft, hardened aircraft shelters, petroleum and logistical storage, ammunition supply bunkers, air defense systems, and radars", a Pentagon spokesman has said.

Captain Jeff Davis said the attack on Shayrat Airfield in Homs governorate was conducted at the direction of US President Donald Trump "in response to the Syrian government's chemical weapons attack".

A total of 59 Tomahawk Land Attack Missiles had been "launched from the destroyers USS Porter and USS Ross in the Eastern Mediterranean Sea," he said.

"As always, the US took extraordinary measures to avoid civilian casualties and to comply with the Law of Armed Conflict," he added. "Every precaution was taken to execute this strike with minimal risk to personnel at the airfield."

Captain Davis also confirmed that Russian forces in the region had been pre-warned about the attack.

US military planned had taken precautions to "execute this strike with minimal risk to personnel at the airfield," he said.

Although they were still assessing the results on the strike, Captain Davis said initial indications were that it had "severely damaged or destroyed Syrian aircraft and support infrastructure and equipment at Shayrat Airfield, reducing the Syrian Government's ability to deliver chemical weapons."

In pictures: US missile strike against Syria Show all 7 1 /7 In pictures: US missile strike against Syria In pictures: US missile strike against Syria The guided-missile destroyer USS Porter (DDG 78) launches a tomahawk land attack missile in the Mediterranean Sea AP In pictures: US missile strike against Syria The United States military launched at least 50 tomahawk cruise missiles at al-Shayrat military airfield near Homs, Syria, in response to the Syrian military's alleged use of chemical weapons in an airstrike in a rebel held area in Idlib province EPA In pictures: US missile strike against Syria Shayrat airfield in Syria Getty Images In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria US Navy guided-missile destroyer USS Ross (DDG 71) fires a tomahawk land attack missile in Mediterranean Sea Reuters In pictures: US missile strike against Syria President Donald Trump speaks at Mar-a-Lago in Palm Beach, Fla., after the US fired a barrage of cruise missiles into Syria in retaliation for this week's gruesome chemical weapons attack against civilians AP In pictures: US missile strike against Syria Syria's President Bashar al-Assad Reuters

He added: "The use of chemical weapons against innocent people will not be tolerated."

Syria decried the attack calling it an "aggression" that led to "losses."

A military official quoted on state TV said material damage had been done to the base.

Another statement, also attributed to an unnamed official, referred to "losses." The officials did not elaborate.

Talal Barazi, the governor of Homs province, where the targeted air base is located, said that most of the strikes appeared to target the province in central Syria.