Starcraft II (And other RTSs)- How should backstabbing be dealt with?

[Archon_Wing]

In many Real Time Strategy games you can form alliances with other players. There's also a "team game" mode where players are on teams. One issue in Starcraft was that a teammate could easily uncheck the alliance and attack you if they wanted to. In Warcraft III, I believe teams are locked which helps stop people from doing this. I assume Sc2 would have something like this.

But the problem is that a teammate doesn't have to unally you to cause you trouble. He/she could attack you with Area of Effect (AOE) spells. It's not viable to make allies invulnerable from AOE; indeed having your allies immune from nukes would break the game probaly. Also, a malicious teammate can place buildings or units to obstruct you. Manual targeting could work, but they could do it too, and if they have units like zerglings, you'd be at a disadvantage. Basically, you might have to be the one to do the unallying to fight back at something like that.

I am not really sure what to do with this. I think allowing unallying and using the Diablo II hostility system would help a bit--a blaring alarm and some delay before the hostility actually starts. Also, if an ally were to use a nuke, that would be indicated on the map to the nuker's allies.

Thoughts? Or is not trusting your allies simply just another part of the Starcraft universe?