What are some fun and interesting alternatives to war that countries could settle their differences with?

Sports competitions.

A game of Crazy 8.

A pair of dice.

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.

This post was edited by JakobA the unAmerican. at September 13, 2017 7:21 PM MDT

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.

2. Pie eating contest.

3. Tug of war.

4. Potato sack race.

5. Egg on a spoon race.

6. Dodgeball.

Shooting marbles...

Have the heads of states at the vanguard of any battle, this is not an alternative to war but it would greatly reduce the number of wars.

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.