How has warfare changed since World War I?

World War I is often described as the first fully modern war. This is true in many ways, and especially inasmuch as it involved the first systematic use of machinery like tanks and airplanes in warfare. Modern war has seen the expansion of these trends to an astonishing degree. The use of air power in particular has become crucial to modern war. That being said, modern war looks considerably different from warfare in the First World War, at least the Western Front. World War I still involved enormous masses of men, arrayed against each other in trenches. Modern warfare tends to be conducted with machinery like tanks and light vehicles along with light infantry, deployed in platoon or squad-sized units. Technology remains crucial in warfare, with "smart" bombs, GPS and laser-guided missiles, and especially drones placing much of the task of killing in the hands of remotely-based controllers. That said, war today, as in World War I, involves individual soldiers putting their lives on the line. It also involves massive destruction, especially for civilians. Increasingly, in fact, the nature of civil conflicts and the "war on terror" has blurred the line between soldiers representing nation-states and and partisan fighters as well as members of international terrorist groups. These terrorist groups have, as recent attacks have shown, brought warfare to "soft targets" like public transportation and civilian buildings in ways that would be familiar to Europeans in the early twentieth century.