"OPCW arrived on Saturday", tweeted the United Kingdom delegation. It has met with Syrian officials but has not visited the town at the center of the controversy.
The U.K. delegation to the OPCW accused the Russian and Syrian governments of hindering the independent investigation into what happened in Douma.
Responding to Haley's remarks about the plans for new sanctions, Evgeny Serebrennikov, deputy head of the defense committee of Russia's upper house of parliament, said Moscow was ready for the penalties, according to RIA news agency.
Russian Federation said it is not curtailing the mission's visit, and appears instead to be blaming the global organization for the delay.
"And in that area where they were used, civilians had a huge order of magnitude greater than the chemical weapon victims killed in the last week or so", he said.
The Kremlin quickly denied reports that Russian Federation was not allowing the OPCW mission in, without elaborating. "We warned that such actions will not be left without consequences", said Anatoly Antonov, the ambassador to the United States, in a statement.
"We had an early warning of the strike from the Russians. and all military bases were evacuated a few days ago", the official said.
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. The OPCW fact-finding team dispatched to Syria to investigate does not have a mandate to assign blame.
The attack was twice as big as one launched by America previous year, which failed to deter Mr Assad.
The UK opposition leader, Jeremy Corbyn of the Labour Party, also questioned the strikes, saying Saturday that he believed the "action was legally questionable", and called on May to publish the UK attorney general's advice that approved the bombings. President Donald Trump immediately said that Syrian President Bashar al-Assad would pay a "big price" and blamed both Russian Federation and Iran for supporting the Assad regime.
In Damascus, hundreds of Syrians gathered on Monday in a landmark square Damascus, rallying in support of their armed forces, which they say succeeded in confronting the airstrikes by the West.
State television broadcast the rally live as participants waved Syrian flags and set off fireworks and celebratory gunfire, according to the AP.
"Bashar Al -Assad will react awfully the reaction will be on the Syrian people not on anyone else". Sayyed Hassan Nasrallah said the U.S. military had kept its strikes limited because it knew a wider attack would spark retaliation from Damascus and its allies and inflame the region.
French President Emmanuel Macron revealed on Sunday that when he spoke to Mr Putin about the strikes he told him Russian Federation was complicit in the use of chemical weapons in Syria.
The Pentagon said Saturday the USA -led allied missile strikes in Syria successfully hit all three targets and have "significantly crippled" Syrian President Bashar Assad's ability to make more chemical weapons.
Damascus sky lights up with service to air missile fire as the U.S. launches an attack on Syria targeting different parts of the Syrian capital Damascus, Syria, early Saturday. The Pentagon said no missiles were engaged.
And in London, British Prime Minister Theresa May was to face an emergency parliamentary debate Monday over her country's part in the operation.
The targets included a scientific research facility near Damascus, and two chemical weapons facilities outside the city of Homs, the U.S. military said, though reports said the buildings had been evacuated in recent days.