DELTA IV IN DRYDOCK, Edward L. Cooper. The Soviet Union designed the DELTA IV submarine to modernize the seaborne leg of its nuclear deterrent force. The Russians built all seven of these nuclear-powered subs in Severodvinsk, launching them at the rate of about one per year from 1985 to 1991. Considered a great success by the Russian Navy, the DELTA IV carries 16 SS-N-23 liquid-fueled intercontinental ballistic missiles. (DIA Military Art Collection)