Branding last week's alleged chemical attack the "crimes of a monster", Trump announced the military action against President Bashar al-Assad's regime in a White House address late Friday, defying fierce warnings from Damascus ally Russian Federation.
Mattis, however, said the assault was a "one-time shot", so long as Assad does not repeat his use of chemical weapons.
"And they have had a very significant impact in degrading their ability to use chemical weapons in the future". It was done on targets that we believed were selected to hurt the chemical weapons program.
France said that its immediate objectives had been met and would push ahead with planned talks with Russian Federation to seek peace.
Saudi Arabia, a key regional ally of the West, has expressed "full" backing for the US-led strikes against Syria and other USA allies Jordan and Egypt called for a political solution while Iraq warned the move could give terrorism an opportunity to expand in the region.
"These are not the actions of a man", Trump said in televised remarks announcing the strikes.
He said: "Bombs won't save lives or bring about peace".
Weapons inspectors will try to reach the site of a suspected poison attack in the Syrian town of Douma, hours after Western countries launched air strikes in retaliation over the gassing.
He attacked the Assad regime for "deploying chemical weapons to slaughter innocent civilians", referring to the alleged atrocity in Douma last Saturday. "And it was not about regime change".
Trump also called out Russia's promise in 2013 that they would guarantee the elimination of Syria's chemical weapons.
The Syrian Government has categorically denied the accusation.
It was not immediately clear when it could be put to a vote.
May on Saturday made her case for action in the face of opposition from much of the public and the Labour Party, saying in a further statement it was highly likely Assad's regime had used chemical weapons.
General Joseph Dunford, chairman of the US Joint Chiefs of Staff, said the allied strikes destroyed three main chemical weapons facilities.
The coordinated strikes included the use of British, French, and US air and naval power targeting three of Assad's chemical weapons facilities.
"Russia calls for an emergency meeting at the U.N. Security Council to discuss the aggressive actions of the United States and its allies".
UN Secretary General António Guterres told the Security Council on Saturday that "The situation in the Middle East is in such chaos that it has become a threat to worldwide peace and security".
Hours after the military operation was completed, Russian President Vladimir Putin condemns the United States and its allies for what it called an "act of aggression" that will exacerbate humanitarian catastrophe in Syria.
The Western missile strikes demonstrate the volatile nature of the Syrian civil war, which started in March 2011 as an anti-Assad uprising but is now a proxy conflict involving a number of world and regional powers and a myriad of insurgent groups.
Before a planned Pentagon briefing Saturday, officials said Air Force B-1B strategic bombers launched JASSM "standoff" missiles for the first time in combat, evading Syrian air defenses.
"This aggression will only lead to inflaming tensions in the world and threatens global security".
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