International inspectors were to begin work on Sunday at the site near Damascus of an alleged chemical attack that prompted an unprecedented wave of Western strikes against Syria's regime.
US, French and British missiles destroyed sites suspected of hosting chemical weapons development and storage facilities, but the buildings were mostly empty and the Western trio swiftly reverted to its diplomatic efforts.
Washington trumpeted the "perfectly executed" strike, the biggest international attack on President Bashar al-Assad's regime during Syria's seven-year war, but both Damascus and Syria's opposition rubbished its impact.
Assad on Sunday denounced a "campaign of deceit and lies at the (United Nations) Security Council" after a push by Moscow to condemn the strikes fell far short.
Syria and its Russian ally are "waging a single battle - not only against terrorism, but also to protect international law based on the respect of the sovereignty of states and the will of their people", Assad's office quoted him saying during a meeting with Russian politicians.
A team of chemical experts from the Organisation for the Prohibition of Chemical Weapons, based in The Hague, arrived in Damascus hours after the strikes.
They have been tasked with investigating the site of an April 7 attack in the town of Douma, just east of the capital Damascus, which Western powers said involved chlorine and sarin and killed dozens.
"The fact-finding team arrived in Damascus on Saturday and is due to go to Douma on Sunday," Syria's Deputy Foreign Minister Ayman Soussan told AFP.
"We will ensure they can work professionally, objectively, impartially and free of any pressure," he said, adding he was confident the experts would prove chemical weapons were never used.
The OPCW itself had declared that the Syrian government's chemical weapons stockpile had been removed in 2014, only to confirm later that sarin was used in a 2017 attack in the northern town of Khan Sheikhun.
US President Donald Trump hailed the pre-dawn strikes that lit up the sky around Damascus as "perfectly executed" and exclaimed "Mission Accomplished" on Twitter.
According to US officials, the operation involved three US destroyers, a French frigate and a US submarine located in the Red Sea, the Gulf and the eastern Mediterranean.
British Tornado and Typhoon warplanes, US B-1 bombers and French Rafale jets also took part in the strikes.
The Pentagon said no further action was planned but Washington's envoy to the United Nations, Nikki Haley, warned that the US was "locked and loaded" should another gas attack occur.
A Western draft resolution obtained by AFP at a meeting of the UN Security Council Saturday calls for unimpeded deliveries of humanitarian aid and enforcement of a ceasefire, along with demands that Syria engage in UN-led peace talks.
French President Emmanuel Macron and other Western leaders have called for a diplomatic offensive after the strikes, aiming to end a conflict that has killed more than 350,000 people and displaced half of Syria's population.
But Russia has blocked countless resolutions against its Syrian ally and the regime has appeared determined to continue its military reconquest of the country.
"For all the sound and fury of these strikes, their net effect is a slap on the wrist of Bashar al-Assad," said Nick Heras, an analyst at the Center for a New American Security.
Regime and allied forces are now expected to train their sights on southern districts of Damascus that are still held by the Islamic State jihadist group.
They are then likely to tackle the southern province of Daraa, where some of the earliest protests against the rule of Assad, in power for 18 years, broke out in 2011.