Although not in active service for many years before 2010, fifty B53s were retained during that time as part of the "hedge" portion[i] of the Enduring Stockpile until its complete dismantling in 2011.

In March 1958 the Strategic Air Command issued a request for a new Class C (less than five tons, megaton-range) bomb to replace the earlier Mk 41.

[15] It was intended as a bunker buster weapon, using a surface blast after laydown deployment to transmit a shock wave through the earth to collapse its target.

Attacks against the Soviet deep underground leadership shelters in the Chekhov/Sharapovo area south of Moscow envisaged multiple B53/W53 exploding at ground level.

It has since been supplanted in such roles by the earth-penetrating B61 Mod 11, a bomb that penetrates the surface to deliver much more of its explosive energy into the ground, and therefore needs a much smaller yield to produce the same effects.

"[16] In its FY2015 budget request, the NNSA noted that the B53 component disassembly was "delayed", leading some observers to conclude they might be the warhead CSAs being retained for potential planetary defense purposes.

[17] The W-53 nuclear warhead of the Titan II ICBM used the same physics package as the B53, without the air drop-specific components like the parachute system and crushable structures in the nose and sides needed for lay-down delivery, reducing its mass to about 6,200 lb (2,800 kg).

[18] On 19 September 1980 a fuel leak caused a Titan II to explode within its silo in Arkansas, throwing the W53 warhead some distance away.

[20] The radiated heat would be sufficient to cause lethal burns to any unprotected person within a 20-mile (32 km) radius (1,250 sq mi or 3,200 km2).

Within 2.25 mi (3.62 km) a 500-rem (5-sievert) dose of ionizing radiation would be received by the average person, sufficient to cause a 50% to 90% casualty rate independent of thermal or blast effects at this distance.