The European Organization for Nuclear Research, known widely as Cern, has confirmed that it will suspend access to its state-of-the-art facilities for roughly 500 scientists affiliated with Russian institutions from 30 November 2024. Cern is an intergovernmental organisation that operates the world’s largest particle accelerator on the border of France and Switzerland.

The restrictions on Russian-based scientists are the outcome of a decision that was initially announced in 2022. The organisation’s cooperation with Belarus ended in late June 2024.

The Cern Council, which has decision-making authority of the organisation, reaffirmed that it has chosen to take this action in light of the ongoing military invasion of Ukraine by the Russian Federation with the involvement of the Belarus. ‘At present, we have less than 500 users still affiliated with a Russian institute, most of them not residing in the region,’ Cern spokesperson Sophie Tesauri stated. She emphasised that the decision of the Cern member states concerns cooperation with Russian institutes, but relations with scientists from Russia and Belarus who are affiliated with Cern under other agreements will continue.

While not a Cern member state, Russia has held observer status for decades. Soon after Russia invaded Ukraine in early 2022, Cern announced that it would suspend Russia’s observer status and would not engage in new collaborations with it. However, the organisation chose not to expel its approximately 1000 Russian users.

The protracted war has added to a significant scientific brain drain in Russia. As of January, the online Russian publication Novaya Gazeta Europe reported that at least 2500 scientists had left Russia since the war began on 24 February 2022.