The global disarmament forum that developed the convention on chemical weapons gained a new leader Monday: Syria. Understandably, the move to recognize a regime accused of widespread chemical attacks against its own people in this way has gone down badly, with one American diplomat labelling it “one of the darkest days in the history” of the forum.

Syria took over Monday as the head of the Conference on Disarmament, an international arms control forum that meets at the Palais des Nations, the home of the United Nations in Switzerland, Geneva.

According to diplomatic protocol, the presidency of the forum is rotated among members every four weeks on an alphabetical basis — so it is Syria’s turn to take over from Switzerland. But the move to recognize one of the most flagrant violators of the prohibition on chemical weapons in this way has been viewed as a travesty by many members.

Robert Wood, the U.S.’s ambassador to the conference, tweeted that Monday “will be one of the darkest days in the history of the Conference on Disarmament with Syria beginning its four-week presidency.”

“The Damascus regime has neither the credibility nor moral authority to preside over the CD. The [international] community must not be silent,” he said.

Wood had earlier called on Russia, one of Syria’s key military and political backers, to ask the regime to sit out its turn in the presidency.

A group of British diplomats joined in the condemnation, issuing a statement that their government “deplores the fact that Syria will assume the presidency of the Conference on Disarmament, given the regime's consistent and flagrant disregard of international non-proliferation and disarmament norms and agreements.”

The statement acknowledged that there was no easy way to stop Syria from receiving the rotating presidency, as to do so would require a consensus among all members of the body, including Syria, for it to stand aside.

“What we will do is ensure the Syrian presidency cannot inflict damage on the work of the Conference of Disarmament and its subsidiary bodies,”

Britain and other member states are expected to voice their objections when the forum meets Tuesday.

The forum has been criticized in recent years as a moribund relic of international diplomacy, with U.N. Secretary General Antonio Guterres saying last week it had produced very little in recent decades.

One of its key achievements however was the development, over 12 years of negotiations, of the convention on chemical weapons, which led to the creation of the Organization for the Prevention of Chemical Weapons — a body which is currently investigating Syria for alleged chemical weapons attacks. The most recent alleged attack on the Syrian town of Douma on April 7 killed scores of people and drove the U.S., France, and the U.K. to carry out missile strikes on Syria in retaliation.

The conference has also negotiated the Nuclear Nonproliferation Treaty, the cornerstone of nuclear disarmament efforts, and the convention against biological weapons.