Pakistan, Aug. 12 -- Eighty years ago today, the first of two atomic bombs was used in anger. Hiroshima and then Nagasaki were vaporised. The Japanese could understand how a thousand-plane B-29 raids could kill one hundred thousand Japanese living in Tokyo or Nagoya in a single night. But it took a second B-29 and a second bomb to shock and awe Japan into abandoning its insistence on suicidal resistance and surrender unconditionally to the Allies.

Then came the H-bomb and thermonuclear weapons. The explosive power of nuclear weapons is measured in thousands of tons of TNT equivalents or kilotons (KT). Thermonuclear weapons are measured in million ton equivalents of TNT (MT). While at one time it was feasible to consider the tactical use ...