The air campaign could frustrate those in Trump's base who oppose military intervention and are wary of open-ended conflicts.
Trump said the strikes were in coordination with France and the United Kingdom, adding that the objective of the campaign is to "establish a strong deterrent against the production, spread and use of chemical weapons".
"The use of chemical weapons by anyone, anywhere, under any circumstances is illegal and utterly reprehensible", Mr Turnbull said.
Russian Federation - a key ally of the Assad government - is calling for an immediate UN Security Council meeting to discuss the "aggressive actions" of the United States and its allies, he said.
She said the United Kingdom would continue to work with global partners to deter the catastrophes caused by chemical weapon attacks and she is "confident of success". "However, we used a little over double the number of weapons this year than we used last year", he said. The targets of that strike included Syrian aircraft, aircraft shelters, petroleum and logistical storage facilities, ammunition supply bunkers, air defense systems and radar. In Homs, one of the missiles was derailed injuring three people, he said.
"So there is no practicable alternative to the use of force to degrade and deter the use of chemical weapons by the Syrian regime", she said.
He said the attack had been limited so far to Syria's chemical weapons facilities and said the facts and the responsibility of the Syrian regime were beyond doubt.
The OPCW had said that its experts would be visiting Douma on Saturday. "This is unacceptable", she said.
A senior Russian official in Damascus, Dmitry Sablin, told the Russian news outlet Tass that he believed the strike was created to interfere with investigations that had already begun into the chemical attack.
War is always unpredictable and risky; the war in Syria, which involves a number of regional powers and two nuclear-armed states, is exponentially more so. Could be very soon or not so soon at all!
"Bombs won't save lives or bring about peace", he said in a statement.
The strikes marked the second time that Trump has attacked Syria to punish the government after it was accused of using chemical weapons.
He added that "those responsible must be held accountable".
The United States allies in the attacks are France and Britain. "The suffering it causes is horrendous".
And he stressed the need "the need to avoid the situation spiraling out of control".
Syrian TV showed police waving Syrian flags apparently on the edge of the town just east of Damascus, and said the "terrorist presence" in Douma will end "in a few hours".
Mr Mattis, who United States officials said had earlier warned in internal debates that too large an attack would risk confrontation with Russian Federation, described the strikes as a one-off to dissuade Assad from "doing this again".
The president on Monday had condemned the suspected chemical attack, calling it a "heinous" act and saying his administration would soon make "major decisions" on how to respond.
Trump said the mandate for an allied attack was open-ended, but Pentagon chiefs later said the strikes Friday would be repeated only if Assad took further action that warranted a response. Russian Foreign Ministry spokeswoman Maria Zakharova said the United States strikes had hit the Syrian capital when the country "finally" had a chance at peace. Attacking Syria is a crime.
Upward of 500,000 people are thought to have died in the seven-year Syria civil war, a conflict that has also driven millions from their homes.
Western air strikes on Syria will not diminish the army's fight against all remaining militants in the country, the military has said in a televised statement. The mission had been a success, she said.
When asked how many missiles were intercepted, Dunford said simply, "I don't know", before stating that the central command would have more details over the weekend.
However, it noted that the missiles were taken down by decades-old systems, including Neva surface-to-air missiles that were designed in the 1950s.
Both Syria and Russia have denied involvement in the attack, which Russian Foreign Minister Sergei Lavrov alleged had been staged.
Witnesses on the ground in Damascus reported hearing explosions in the Syrian capital, where more than a million people live.
Moscow hardly needed a heads up that military action was coming.
The US, UK and France coordinated to launch strikes against targets within Syria in response to an alleged chemical weapons attack by the regime of President Bashar al-Assad.
Hundreds of Syrians are demonstrating in a landmark square of the Syrian capital, waving victory signs and honking their auto horns in a show of defiance.
All but six were confirmed to have been conducted by the Syrian government. Some clapped their hands and danced, others drove in convoys, honking their horns.
"We are your men, Bashar", they shouted.
"Good morning steadfastness", one broadcaster said.
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