The United States joined its NATO allies Tuesday in launching a pressure campaign against the use of chemical weapons in Syria, while singling out Russia for protecting Syrian President Bashar al-Assad’s regime.

“The recent attacks in East Ghouta raise serious concerns that Bashar al-Assad’s Syrian regime might be continuing its use of chemical weapons against its own people,” U.S. Secretary of State Rex Tillerson said in Paris.

Tillerson said at least 20 people were killed Monday in an apparent chlorine gas attack in rebel-held East Ghouta, near Damascus.

He singled out Russia and its support for the Assad regime.

“Whoever conducted the attacks, Russia ultimately bears responsibility for the victims in East Ghouta and countless other Syrians targeted with chemical weapons since Russia became involved in Syria,” said Tillerson during a conference hosted by French Foreign Minister Jean-Yves Le Drian on an initiative to target those responsible for chemical attacks.

Tillerson, along with foreign ministers from France, Germany and Turkey, were among those who on Tuesday launched the International Partnership Against Impunity for Use of Chemical Weapons. More than two dozen like-minded nations endorsed a political commitment to share information on combating the use of chemical weapons worldwide.

The U.S. secretary of state said Russia’s failure to resolve the chemical weapons issue in Syria called into question its commitment to the resolution of the overall crisis.

“At a very minimum, Russia must stop vetoing and at least abstain from future security council votes on this issue,” Tillerson said.

Russia used its council veto last year three times to prevent the so-called Joint Investigative Mechanism, or JIM, from carrying out its mandate to find out who had perpetrated chemical weapons attacks in Syria. Its third veto, in November, effectively killed the mechanism.

In New York, the Russians hastily called a Security Council meeting Tuesday afternoon. 

Russian envoy Vassily Nebenzia criticized the JIM as a “complete failure” and a “mechanism of political manipulation.” He said Russia was circulating a draft resolution proposing a new mechanism.

“We wish to rise above these differences and to propose the establishment of a new international investigative body, which, on the basis of irreproachable and corroborated information received from transparent and credible sources, would be able to establish evidence for the Security Council to identify perpetrators in the use of chemical weapons or chemical warfare agents,” Nebenzia told council members. “This mechanism needs to be professional, and it must be an apolitical mechanism.”

But U.S. Ambassador Nikki Haley appeared to reject the Russian proposal.

“We’re not going to accept any Russian proposal that undermines our ability to get to the truth or that politicizes what must be an independent and impartial investigation,” she said. “If they want to work in good faith toward that goal, we are ready to re-establish the JIM, with its original independent and impartial mandate, right now. But anything less is unacceptable.”

Haley criticized Russia for accepting the JIM’s conclusions when they pointed to Islamic State militants being responsible for gas attacks, but not when they found the Assad regime culpable.

Turkey’s Afrin offensive

Turkey’s offensive in the northern Syrian enclave of Afrin was also a focus of Tuesday’s talks in Paris, with Tillerson meeting with his Turkish counterpart, Mevlut Cavusoglu. A day earlier, during remarks in London, the top U.S. diplomat said the United States was “concerned” about the offensive against U.S.-backed Kurdish YPG fighters in Syria.

Turkish forces intensified military operations Monday to push the Kurdish militia out of the Afrin area.

The Turkish operation is aimed at ousting from Afrin the Syrian Kurdish group that has controlled territory in northern Syria and proven effective in the U.S.-coalition-led fight against Islamic State militants.

Turkey considers the YPG to be a terrorist organization associated with the outlawed Kurdistan Workers’ Party, or PKK, which has fought for Kurdish autonomy in Turkey.

French Foreign Minister Le Drian on Tuesday joined Tillerson in expressing his concern about Turkey’s military operation in Afrin.

“I had the opportunity to tell my Turkish colleague that this offensive worries us,” Le Drian said.

“While we understand the concerns Turkey has about border security, we cannot but call on Turkey to show the greatest level of restraint on this issue,” the French foreign minister added.

Turkey’s shelling into Afrin came after the U.S.-led coalition said it would form a 30,000-strong Kurdish-led border security force in northern Syria.

Washington later said the effort had been mischaracterized and that the U.S. was not creating a border force, but that the coalition would provide security to liberated areas, blocking escape routes for Islamic State militants.

VOA’s Margaret Besheer contributed to this report from the United Nations.