Russia came under fire at the session for alleged meddling at the Douma attack site. An OPCW fact-finding mission from the chemical weapons watchdog is currently on the ground there investigating the alleged use a poisonous gas on civilians by forces of Syrian President Bashar Assad.
In the closed-door session, US Ambassador Kenneth Ward also accused Russia of tampering with evidence in Douma.
"It is our understanding the Russians may have visited the attack site. It is our concern that they may have tampered with it with the intent of thwarting the efforts of the OPCW Fact-Finding Mission to conduct an effective investigation," Ward told Reuters.
France: Syria has 'secret' chemical weapons program
The French representative to the OPCW, Phillipe Lalliot, told the group on Monday that "[they] all know" Syria has maintained a secret chemical program since 2013. Syria joined the organization that year, following a deadly sarin gas attack on civilians in Ghouta. The government agreed to the destruction of its chemical weapons stockpiles, though some have questioned whether this was fully completed.
Lalliot also said that the technical team must be supported so it can completely dismantle Syria's "secret" weapons program.
OPCW investigators are collecting samples, interviewing witnesses and documenting evidence to determine whether chemical weapons were used.
Wilson also had critical words for the OPCW itself as he called for the Executive Council members to hold Syria responsible.
"The time has come for all members of this Executive Council to take a stand. Too many duck the responsibility that comes with being a member of this council," he said. "Failure to act to hold perpetrators to account will only risk further barbaric use of chemical weapons, in Syria and beyond."
Russia fires back at the US
Russia, which found itself accused of persistently obstructing chemical weapons investigators work, fired back at its critics.
Russian Deputy Foreign Minister Sergei Ryabkov denied that Russia was blocking the OPCW fact-finding mission in Douma, saying that the investigators had not been allowed in because they lacked the necessary UN security permit.
Additionally, the Russian Embassy in the Hague tweeted that the US "tries to undermine the credibility" of the OPCW mission in Syria. Russia also said it "confirms its commitment to ensure safe (sic) and security of the mission and will not interfere in its work."
A senior Russian official said after the meeting the OPCW experts were expected to arrive in Douma on Wednesday.
"Tomorrow [Tuesday] the security services of the United Nations ... will test the routes. And on Wednesday is when we plan the arrival of the OPCW experts," Russian Defense Ministry official Igor Kirillov said at a news conference at the Russian embassy in the Hague. He said routes into Douma were still being cleared of mines.