War in the 20th century featured more or less traditional elements, including trench fighting by soldiers with guns in World War I and WWII. The advent of the airplane raised the stakes– including suicide missions of Japanese Kamikaze pilots as well as the ability to drop large bombs on entire cities. The Vietnam War too, was a lot of, almost you could say hand-to-hand soldier combat.
What is coming now, however, is an incredibly threatening type of warfare that could combine many disastrous elements into new defense weapons that are so unconventional and frankly scary terrorizing to think about.
Drones such as the Kalashnikov KUB-UAV drone here by a Russian company are sophisticated and yet only hint at how devastating future war could be. At just 4-feet wide and weighing not so much, almost anyone, even beyond traditional military, could deploy such a weapon, programming and/or controlling it to a target miles away, and it would be pretty hard to defend against.