War has always caused negative effects for both the sides. There is really never in a war, other than the fact that you captured the enemy's land or killed the tyrant.
In a war, a country must spend a lot of money to send troops, supplies, artillery (tanks, rockets, missiles). This money could have been spent in giving more homeless children food or better education for children.
In a war, many landmarks and resources can be destroyed. Soldiers are dying, hence the population is being brought down. Families are breaking up, brothers are losing brothers, mothers are losing sons etc.
On top of that, in a war many innocent people are killed mostly by bombs. Countries usually go into a huge debt after a war has taken place. War hardly has positive effects, the negative effects outweigh them very badly.
Think positive! Think War-Free