The U.S. -led coalition strikes in Syria were created to deter President Bashar Assad's regime from launching further chemical attacks without collapsing his shaky government and drawing the United States further into a lengthy civil war.
"A combined operation with the armed forces of France and the United Kingdom is now underway", President Trump said in an address to the nation.
U.S. Defense Secretary Jim Mattis later said that Washington was still analyzing intelligence related to Saturday's suspected chemical weapons attack.
British Cabinet ministers have agreed "on the need to take action" in Syria to "deter the further use of chemical weapons", Downing Street has said.
U.S. ambassador Nikki Haley said: "It is Russian Federation alone that has stopped at nothing to defend the Syrian regime's multiple uses of chemical weapons".
White House spokesperson Sarah Huckabee Sanders said Wednesday Trump "holds Syria and Russian Federation responsible for this chemical weapons attack", and said "all options are on the table".
The President said the US strikes on Syria, were launched in concert with British, French allies.
Russian Federation has been a staunch ally of Syrian President Bashar Assad's government and has helped turn the tide of war in his favour since entering the conflict in September 2015.
Mattis said the United States during the Obama administration tried to deal with the chemical weapons when he was enlisting the Russians, who were complicit in the Assad regime retaining those weapons. Syrian television reported that a scientific research center had been hit.
"The president has not made that decision", he said.
"This massacre was a significant escalation in a pattern of chemical weapons use by that very bad regime", Trump said.
Russia Wants UN Chief At Meeting On US Threats
Russian Federation also could fire at the launch platforms used - potentially USA planes or ships. It is unclear how such a vote might turn out.
"We hope that. the USA and their allies will refrain from military action against a sovereign state", said Russian Ambassador to the U.N. Vassily Nebenzia.
Some lawmakers criticized Trump's apparent telegraphing by tweet of a missile strike in Syria.
EARLIER: US President Donald Trump has confirmed "precision strikes" against Syria are underway.
The U.S.is conducting the strikes in coordination with Britain and France, the president said.
"We are prepared to sustain this response until the Syrian regime stops its use of prohibited chemical agents".
"We call upon... members of the worldwide community to seriously consider the possible consequences of such accusations, threats and especially action (against Syria)", Russian foreign ministry spokeswoman Maria Zakharova said.
Statements from Washington have been militaristic, ministry spokeswoman Maria Zakharova said, and threats by the U.S. and France were a violation of the United Nations charter.
Anti-aircraft fire is seen over Damascus, Syria early April 14, 2018.
The strikes seemed unlikely to have much impact on the balance of power in Syria's seven-year-old civil war, in which Assad's government has steadily gained the upper hand against armed opponents since Russian Federation intervened in 2015.
In that strike, on April 7, 2017, the USA launched 59 cruise missiles on a Syrian military airbase. The Syrian government has repeatedly denied any use of banned weapons.
A team of experts from the global chemical weapons watchdog, the Organisation for the Prohibition of Chemical Weapons, was travelling to Syria and will start its investigations into the Douma incident on Saturday, the Netherlands-based agency said.