It is a combination of a military "class" whose careers advance by having conflict, and the manufacturers and various others who profit from conflict. These groups will presumably combine to lead the people of a country in to wars that serve mainly to benefit those groups.

This, of course, lets the people of the country you are discussing off the hook for the actions of their government, which is by and large HOOOOOOOOOOORSE SHIT. People love wars, until they decide they were against it all along, which always happens after there is not the quick victory they thought would happen.

Also, FUN FACT- This was regarded as some kind of peacenick pronouncement against war when Eisenhower warned against it. This is not so, what Ike objected to was large scale, conventional wars. He was the man whose administration oversaw many of the coups of the cold war, and set policies that would see the 3rd world in flames for decades. He just did not want to use american soldiers and tanks to do it.