Captain 2nd rank (Russian: капитан 2-го ранга, romanized: kapitan vtorogo ranga, lit. 'captain of the 2nd rank') is a rank used by the Russian Navy and a number of former communist states. The rank is the middle rank in the staff officer's career group. The rank is equivalent to lieutenant colonel in armies and air forces. Within NATO forces, the rank is rated as OF-4 and is equivalent to commander in English-speaking navies.[1]