On October 3, 1986, K-219 was cruising approximately 600 miles northeast of the island of Bermuda.

On October 3, 1986, K-219 was cruising approximately 600 miles northeast of the island of Bermuda.

The ballistic missile submarine was designed to carry nuclear-tipped missiles within range of the United States as part of the USSR's nuclear deterrent

The ballistic missile submarine was designed to carry nuclear-tipped missiles within range of the United States as part of the USSR's nuclear deterrent

A month after leaving the Soviet Northern Fleet's Gadzhiyevo submarine base, the K-219 was conducting launch exercises, preparing for the day it could launch its nuclear-tipped missiles off the East Coast of the United States

The K-219 was a "Yankee" class submarine, a NATO intelligence designation likely referring to the submarine's uncanny resemblance to early US Navy George Washington-class ballistic missile submarines.

Unlike previous Soviet missile submarines, which stored their long missiles in the sail, the Yankee class stored shorter, more compact missiles in the hull behind the sail, in a raised hump, just like American submarines.

At 420 feet long and 38 feet beam, the Russian submarine was a long and lean nuclear-armed predator. The K-219 had a maximum submersible depth of 1,029 feet and a crew of approximately 120.

At 420 feet long and 38 feet beam, the Russian submarine was a long and lean nuclear-armed predator. The K-219 had a maximum submersible depth of 1,029 feet and a crew of approximately 120.

Powered by two 90-megawatt OK-700 nuclear reactors, she could travel underwater at a speed of 27 knots and had a range limited only by her food and water supply

Powered by two 90-megawatt OK-700 nuclear reactors, she could travel underwater at a speed of 27 knots and had a range limited only by her food and water supply

Each R-27U had a range of 1,900 miles. Its accuracy—measured as circular error probable (CEP), or the maximum distance from the target at which half of the warheads hit—was 1.2 miles

Each R-27U had a range of 1,900 miles. Its accuracy—measured as circular error probable (CEP), or the maximum distance from the target at which half of the warheads hit—was 1.2 miles

This relatively poor accuracy required a large, civilization-choking warhead to balance it; as a result, each missile carried one megaton thermonuclear warhead or three separate 200-kiloton warheads

This relatively poor accuracy required a large, civilization-choking warhead to balance it; as a result, each missile carried one megaton thermonuclear warhead or three separate 200-kiloton warheads

On that day in 1986, K-219 was sailing submerged in the Sargasso Sea when a rocket fuel leak caused an explosion. A standard procedure aboard a nuclear-powered ship to prevent fire from breaking through the reactors.

The accident killed four crew members (one of whom died when the reactors were shut down) and injured an unknown number of others

The accident killed four crew members (one of whom died when the reactors were shut down) and injured an unknown number of others

The accident resulted in the loss of at least 16 thermonuclear warheads as well as two nuclear reactors.

The accident resulted in the loss of at least 16 thermonuclear warheads as well as two nuclear reactors.

Admiral Vladimir Chernavin, then head of the Soviet Navy, explained to the Soviet leadership that the high explosive and plutonium aboard each nuclear warhead were contained in metal spheres