The US has hit three targets in Syria in what President Donald Trump called “precision strikes” in coordination with the UK and France.

The Pentagon confirmed the first wave of strikes is complete as a response to a suspected chemical weapons attack on the city of Douma, where 60 people were reported killed and 1,000 injured. The three targets hit included a scientific research centre in the greater Damascus area used for research, development, production and testing of chemical weapons; a facility just west of Homs which is thought to be centre for sarin gas production and “precursor production equipment;” and a command post located near the first facility, said Chairman of the Joint Chiefs of Staff General Joseph Dunford.

Defence Secretary James Mattis repeatedly said at a news conference that the targeted but “heavy” strike tonight was “directed at the Syrian regime” and that the allies have “gone to great lengths to avoid civilian casualties”. However, he was unable to guarantee that there were no caches of already-produced chemical weapons in these facilities that, if destroyed during the strike, could leak and harm nearby civilian populations.

The allies reviewed several sites, but these three were chosen because of the significance to the overall chemicals weapons programme of President Bashar al-Assad.

The US, just three months into Mr Trump's presidency in 2017, had launched 59 Tomahawk missiles to strike the Shayrat air base in the Idlib province, where US intelligence pointed to as the source of a chemical weapons attack on the town of Khan Shiekhoun last year, where 86 civilians had been reported dead from the use of sarin gas.

"Clearly the assad regime did not get the message last year," Mr Mattis said.

Emmanual Macron says France has prood the Assad used chemical weapons in Syria

Mr Dunford explained the 2017 strike was a unilateral use of force with a single target, whereas today’s strike was in coordination with two allies, had multiple targets, and sought the “long term degradation” of the regime’s chemical weapons capabilities.

“Important infrastructure was destroyed,” the regime has lost years of research, data, and expensive equipment, Mr Dunford said.

In his announcement earlier, Mr Trump blamed Russia for the regime's use of chemical weapons on civilians. The US and Russia have exchanged several diplomatic barbs at the United Nations over the past week over the matter investigating the alleged Douma attack.

The White Helmets assist in Douma, Syria Show all 14 1 /14 The White Helmets assist in Douma, Syria The White Helmets assist in Douma, Syria Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces EPA The White Helmets assist in Douma, Syria epaselect epa05635971 Volunteers of the Syrian Civil Defense, also known as the White Helmets, carry large pieces of burned wood as they try to extinguish a fire after a bombing in Douma, on the outskirts of Damascus, Syria, late 17 November 2016. According to local reports, at least six people were killed and 30 injured in several bombings mostly throughout the night. EPA/MOHAMMED BADRA EPA The White Helmets assist in Douma, Syria epaselect epa05636079 A volunteer of the Syrian Civil Defense, also known as the White Helmets, looks at a burning structure after a bombing in Douma, on the outskirts of Damascus, Syria, late 17 November 2016. According to local reports, at least six people were killed and 30 injured in several bombings mostly throughout the night. EPA/MOHAMMED BADRA EPA The White Helmets assist in Douma, Syria Members of the Syrian Civil Defense, known as the White Helmets, extinguish fire following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus, on November 17, 2016. Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces. / AFP PHOTO / Sameer Al-DoumySAMEER AL-DOUMY/AFP/Getty Images Getty The White Helmets assist in Douma, Syria A Syrian man searches for victims as fire spreads following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus Getty The White Helmets assist in Douma, Syria Members of the Syrian Civil Defense, known as the White Helmets, extinguish fire following a reported government airstrike on the rebel-held town of Douma Getty The White Helmets assist in Douma, Syria Members of the Syrian Civil Defense, known as the White Helmets, extinguish a fire following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus Getty The White Helmets assist in Douma, Syria Syrians run for cover following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus Getty The White Helmets assist in Douma, Syria Members of the Syrian Civil Defense, known as the White Helmets, search for victims following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus, on November 17, 2016. Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces. / AFP PHOTO / Sameer Al-DoumySAMEER AL-DOUMY/AFP/Getty Images Getty The White Helmets assist in Douma, Syria A Syrian man searches for victims following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus, on November 17, 2016. Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces. / AFP PHOTO / Abd DoumanyABD DOUMANY/AFP/Getty Images Getty The White Helmets assist in Douma, Syria A member of the Syrian Arab Red Crescent searches for victims following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus, on November 17, 2016. Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces. / AFP PHOTO / Abd DoumanyABD DOUMANY/AFP/Getty Images Getty The White Helmets assist in Douma, Syria Injured Syrian men receive treatment at a makeshift hospital following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus, on November 17, 2016. Douma, the largest town in the Eastern Ghouta area with more than 100,000 residents, is surrounded and regularly shelled by regime forces. / AFP PHOTO / Abd DoumanyABD DOUMANY/AFP/Getty Images Getty The White Helmets assist in Douma, Syria An injured Syrian man receives treatment at a makeshift hospital following a reported government airstrike on the rebel-held town of Douma Getty The White Helmets assist in Douma, Syria Injured Syrians receive treatment at a makeshift hospital following a reported government airstrike on the rebel-held town of Douma, on the eastern outskirts of the capital Damascus, on November 17, 2016. EPA

He noted that there had been no Russian response to the strikes that he was aware of at the time, but that there was "surface to air missile activity" from Syrian forces that the US had observed. Mr Dunford also explained that the US did not warn Russian forces on the ground about the strikes aside from using a "deconfliction channel," or a continuously open line of communication between parties, to clear up airspace. Using that channel is a standard procedure for all US operations in Syria.

The US strike did involve manned aircraft, but neither Mr Mattis nor Mr Dunford was able to comment on further details. There are no losses to report at the moment.

Until yesterday, Mr Mattis had not been confident there was enough evidence to suggest Mr Assad's regime was responsible for the Douma attack, but tonight said he had an "intelligence level of confidence" it was. He noted that chlorine gas was likely one of the agents used in the attack as well, though there could have been others. Investigators from the Organisation for the Prohibition of Chemical Weapons (OPCW), endorsed by United Nations Secretary-General Antonio Guterres, have asked for access to Douma to the rebel-held town as well.