Drawing the lines
Japan had a watergun fight today:
http://www.aljazeera.com/news/asia-pacific/2012/09/20129255327498152.html
The question is, does a watergun fight constitute an act of war? With a backing of personal experience, my answer would be no, unless, however, one of the parties fills its watergun tanks with either hot water or urine, in which case it would be on like donkey kong.
totorobaga 