Western powers blamed President Bashar al-Assad, but Syria and its ally Russian Federation categorically denied the claims and accused the West of "fabricating" the incident to justify military action.
That in turn raises the question of where Western countries go from here, after a volley of strikes denounced by Damascus and Moscow as both reckless and pointless.
Britain's Prime Minister Theresa May was more cautious, but by the time the first precision cruise missile was launched, Trump had a mini-coalition. French President Emmanuel Macronsaid in a statement that a target of the strike was the Syrian government's "clandestine chemical arsenal".
While Trump, along with French and British allies, insisted that airstrikes were necessary to deter Syria's use of chemical weapons, Russian Federation maintains that there's no evidence chemical agents were used.
Military from the three nations launched a missile strike on three facilities in Damascus following last week's chemical weapon attack in the suburb of Duoma, which killed 40 civilians.
The other two were storage facilities around Homs, a city to the north of Damascus.
A San Diego-based destroyer was among four Navy vessels that fired dozens of cruise missiles early Saturday morning local time in the attack on Syrian chemical weapons sites.
The strikes carried out by the United States, Britain, and France were aimed at "degrading the Syrian regime's capability and deterring the use of chemical weapons", she said.
"After seven years of war, we don't believe that anyone will come to help the Syrian people anymore", he said. Fractured opposition forces have had varying levels of support from the West, Arab states and Turkey.
Damascus skies erupt with surface to air missile fire as the US launches an attack on Syria targeting different parts of the Syrian capital Damascus, Syria, early on April 14, 2018.
The Syrian government has denied responsibility and Russian Federation has suggested Israel or Britain was to blame, the latter to justify increased western intervention into the war-ravaged country.
The Western strikes will do little to slow the military reconquest which, with backing from Russian Federation and Iran, has seen Assad reclaim more than half of Syrian territory.
Speaking to the press from Downing Street on Saturday morning, she described the joint action with the USA and France as "limited, targeted and effective" and insisted the aim was not to bring about regime change.
"If it is finished, and there is no second round, it will be considered limited", the official said. Mattis disclosed that the US had not yet confirmed that the most recent suspected Syrian chemical weapons attack, on April 7 in the Damascus suburb of Douma, included the use of sarin gas.
Russian ambassador Anatoly Antonov said on Twitter: "A pre-designed scenario is being implemented".
"The aggression is a flagrant violation of global law, a breach of the worldwide community´s will, and it is doomed to fail", said state news agency SANA. An official in Iran's Revolutionary Guards said it would cause consequences that were against us interests. Smoke could be seen emerging from the northern and eastern edges of the capital.
The U.S. -led strike was a response to a purported chemical attack on civilians in the Syrian town of Douma on April 7.
Syrian state media said the country's "air defenses shot down 13 missiles south of Damascus", NPR's Ruth Sherlock reports from Beirut. "No other group" could have carried out that attack, she said, adding that the allies' use of force was "right and legal".
Syria's state-run news agency SANA reported at least three civilians were wounded in the strikes. Evidence that the nerve agent sarin also was used was inconclusive, he said. At a Pentagon news conference alongside Mattis, and with British and French military officers beside them to emphasize allied unity, Dunford said the attacks targeted mainly three targets in western Syria. "All of these symptoms are characteristic of a chemical weapons attack, particularly choking agents and organophosphorus agents or hydrocyanic acid". The treaty does, however, prohibit the use of chlorine as a weapon. The official said this could require a more sustained USA air and naval presence in the region, as well as more surveillance. Just weeks ago, Trump said he wanted to end US involvement in Syria and bring American troops home to focus on the homeland.
"America does not seek an indefinite presence in Syria, under no circumstances", Trump said in his address.
The use of chemical weapons, such as chlorine, sparks worldwide indignation but is far from being the most lethal weapon in the regime's arsenal.
These hardliners, along with influential United States allies Israel and Saudi Arabia, want Washington to counter Iran's growing power in Syria - even if it means risking a perilous stand-off with Russian Federation.
The Pentagon assessed that nerve agents were present in the Barzah research center and that the Syrian regime employed about 40 surface-to-air missiles, but those launches occurred after the last impact of the U.S. and its allies' strike.