4. US used napalm, dumped 20 m gallons chemicals on Vietnam during 1962-1971
The picture of a young naked Vietnamese boy screaming with his back on fire due to napalm is now part of historic folklore.
As a result of the decade-long chemical attack, 400,000 people were killed or maimed, 500,000 babies have been born with birth defects, and 2 million have suffered from cancer or other illnesses.