for a war to happen, one leader will have to be ultra agressive and sure of themselves, and will probably only commit troops if their numbers far outweigh the opposition. each side will use the internet and the media to try and dissuage the other from fighting and will try to cripple each others informatino resources.
special forces units, with thier capabilitiy to strike enemy supply lines and to operate behind enemy lines will mean that in the event of an invasion, armies will not really want to extend themselves too far, thus delaying their progress and wasting time, resources and lives
ultimately, politicians, with thier reluctance to have any casualties and thier utter spinelessness, will have the most negative affect on war. thier pressure on commanders will lead the commanders to not act as boldly and decisively as they could as they will constantly be being second guessed by politicians.
and as always the media will see something, report it, and desort it