"The Federal Security Service has thwarted an attempt by Ukraine's secret services to commit a terrorist attack on one of the ships of the Black Sea fleet that carries high-precision missiles. As a result of measures, a serviceman of the Russian Navy recruited by Ukraine's secret services was detained, with two self-made explosive devices with a total weight of 1 kilogram of TNT," the FSB said in a statement.
The detainee is also suspected of the transfer of information constituting state secrets, the service added.