NV would win, they can genjutsu soldiers into fighting for them using those damned uchiha and gain all relevant info needed using the ino clans mind control/reading and they also have that pesky transformation jutsu that would reak all sorts of havoc among our moral. Obito could have the US nuke itself. Ninja are also fast enough the fight us using melee weapons while we have guns, but once the military gets infiltrated by genjutsu'd soldiers it's only a matter of time, but the biggest danger lies in having all our weapons turned against us which would most likely be the case.