Russia’s top investigative body announced Monday that it had opened a “criminal” case against the prosecutor and judges of the International Criminal Court (ICC).

The move comes as part of a concerted effort from Moscow to intimidate the court in the Netherlands, which on Friday issued an arrest warrant for Russian President Vladimir Putin over his part in “unlawful” forced deportations of Ukrainian children to Russia.

Former Russian President Dmitry Medvedev threatened earlier Monday to target the court in The Hague with missile strikes.

“It is quite possible to imagine a hypersonic missile being fired from the North Sea from a Russian ship at the Hague courthouse. Everyone walks under God and rockets. Look carefully to the sky … ” he said.

Russia began criminal cases against the prosecutor Karim Ahmad Khan and judges Tomoko Akane, Rosario Salvatore Aitala and Sergio Gerardo Ugalde Godínez on the basis of them having committed “signs of crimes” under Russian law. This includes knowingly accusing an innocent person of a crime in Khan’s case, and deliberately unlawful detention in the cases of the judges.

The court officials are also suspected of “preparations for an attack on a representative of a foreign state enjoying international protection, in order to complicate international relations.” Moscow has previously said it does not recognize the ICC’s authority.

Both Putin and Russia’s commissioner for children’s rights, Maria Lvova-Belova, were hit by the ICC arrest warrant last week, which will severely limit Putin’s potential range of diplomatic visits.