Mist Ninja aren't allowed in Wind Country and Sand Ninja aren't allowed in Water Country.
Apparently, ANBU are also patrolling the streets.
So, what if Sand Ninja could "sneak into" Water Country (Mist "sneak into" Wind Country)? But when sneaking into the country, they will be forced to fight a group of ANBU (5 ANBU, all 2 levels higher?) and if they manage to beat the ANBU, they have access to the opposing country for X many clicks (meaning, they can only click so many times while in that country). If they lose, they will die and lose 15% of experience.
I thought of this because of how it would make sense that this would be attempted during a war and I think some people want more of a chance to slay the enemy (all Mist seem to be hiding in Water and all Sand are hiding in Wind). It'll give Sand to attack Water and Mist to attack Wind.