Russia’s parliament voted Tuesday to revoke ratification of the Comprehensive Nuclear Test Ban Treaty in the first of three readings, raising fears that Moscow will resume nuclear testing.

Members of the State Duma, Russia’s lower house of parliament, voted unanimously—412 votes to zero—to revoke Moscow’s ratification of the treaty. The bill must pass three readings in the lower house and receive approval from the upper house before it is sent to Russian President Vladimir Putin‘s desk to be signed into law.