French President Emmanuel Macron also said he had "proof" that the Syrian government had attacked Douma with chemical weapons.
Wednesday: Russia's Foreign Minister Sergei Lavrov said Russian military inspectors found no evidence of a chemical attack.
Some national leaders appeared anxious to avert a U.S. Russian Federation has air and naval bases in Syria, but its forces are dwarfed by those of Iran, which is also fighting on behalf of Assad, and of the USA and its allies. He accused the United States, France and Britain of "demonstrating a blatant disregard for worldwide law".
Turkish President Recep Tayyip Erdogan says he has urged calm and efforts to restitute peace in Syria during separate calls this week with U.S. President Donald Trump and Russia's President Vladimir Putin.
"Just deterring this act with a few airstrikes and not looking at the consequences for Syria wouldn't be a fully fleshed-out action", said another senior administration official.
In Damascus, "hundreds of residents began gathering in the landmark Omayyad square of the Syrian capital".
But none of those any longer directly threaten Assad's grip on power, which has been reinforced by Russian air power and Iran-backed fighters on the ground.
"Good souls will not be humiliated", Syria's presidential office tweeted, as translated by the AP.
The U.S., the possessor of the biggest arsenal of chemical weapons, has no moral right to blame other countries. France said Russian Federation was warned in advance of the strikes to avoid direct confrontation. "The Russian-made air defense systems supplied to Syria have demonstrated their efficiency". Officials said all weapons hit their marks, which were three facilities that were a part of President Bashar al-Assad's chemical weapons program. "Assad's recent attack, and today's response, are the direct result of Russia's failure to keep that promise". "It is not about regime change".
Russian Federation and Iran have called the action a "military crime" and "act of aggression".
In a statement later on Saturday morning in London, May said the United Kingdom was "confident of its success".
Konstantin Gaaze, a liberal independent analyst here, said Friday that Putin still hopes to negotiate a new start to U.S.
A team from the Organization for the Prohibition of Chemical Weapons is in Syria to investigate the Douma incident and was expected to visit the town.
North Atlantic Treaty Organisation members Germany and the Netherlands have said they will not take part in any military action. He didn't elaborate or name the state.
Turkey's foreign ministry said the airstrikes were "an appropriate response to the chemical attack".