Russian Roulette played by the 2 Heads of State involved (If the issues between them are not serious enough for both of,them to play willingly warfare is out)
Alas, all this entirely ignore terrorism and 5th column activities.
1. Instead of guns, I think each soldier should be given a large feather. They should then line up, naked, each army facing the other and, at the agreed upon signal, they tickle each other. The first person to fall down in hysterics loses the fight for his/her country.
There isn't any. John Lennon as much as I liked the dude is wrong. Peace doesn't work. It's okay to fulfill your side of the bargain, but if an other country sees it as a sign of weakness, they will take advantage of you. That's the way the world works. Dog-eat-dog. It's nature.
The person that defines what a country is, is the one who should be in the vanguard of any conflict over a line on a map. We all come from this world, it is our world, we must all live in this world regardless of political/religious lines on maps.