WASHINGTON, April 18 (UPI) -- In contrast to the stately, apparently leisured way long-range aircraft have evolved in their capabilities and weapons systems over the past half century, the evolution of land weapons systems appears more like life in a tropical jungle, with a bewildering number of weapons systems evolving or neutralizing each other and then being killed off in their turn, only to re-emerge in other conflicts, in a bewildering kaleidoscope of movement.

If one is looking at all kinds of war and weapons systems rather than just the pricey, high-tech ones that get all the publicity in the specialist journals, one has to conclude that in the second half of the 20th century the most effective killing weapons became less advanced by the year. It was like a mad gallop back to the Stone Age.

World War II was ended by fleets of state-of-the-art American submarines starving the home islands of Japan while unprecedented, pressurized long-range, high-speed Boeing B-29 Superfortress strategic bombers burned Japan's cities to cinders. The war was ended by the strategic impact of the dropping of two atomic bombs on the Japanese cities of Hiroshima and Nagasaki.

Yet in 1994 at least as many people were killed in Rwanda by being hacked to death with machetes as were killed in Hiroshima and Nagasaki.

Other Third World genocides of the 20th century such as the Killing Fields of Cambodia in the late 1970s or the slaughter of around half a million to a million ethnic Chinese in Indonesia in 1966 were also carried out with nothing more than knives.