Crucially they've been named as leading an international conspiracy to obtain semiconductors, radars and satellites used in advanced US military systems in order to provide them to Russia's defense sector.

Artyom Uss, who is son of the wealthy governor of the Siberian region of Krasnoyarsk and a Kremlin "insider", was arrested by Italian agents at Milan's Malpensa Airport this week upon US request, while Yury Orekhov was detained Monday in Germany. Both now face extradition proceedings.

"We are categorically against this and we condemn the practice of these kinds of arrests of Russian citizens," Kremlin spokesman Dmitry Peskov said in a Friday press briefing, pledging Moscow will do "everything possible" to defend them and seek their return. "Our diplomatic missions will naturally take part in protecting the interests of this Russian citizen," Peskov added.