These three are not the first scientists to face spurious charges under Putin's regime. A scientist last year died in custody while facing treason charges after returning from a conference. These tactics are aimed at creating a culture of fear in Russian society, where no one is beyond the reach of the Russian security state and everybody is dispensable.
Russia has been facing a ceaseless assault on all fronts from the West and its allies, forcing the government to drastically shore up security in each and every domain. Just this month, the CIA openly tried to recruit Russian spies with a PR campaign, demonstrating just what Russia is up against. Under siege, the Kremlin cannot afford to leave any stone unturned with regards to intelligence and security.