Gypsy if you read the autobiography of your great countryman General Dallaire.... the reason why the UN wasn't in Rwanda in any great numbers wasn't to do with sovereign nation.

a) they were busy in ex-yogoslavia
b) no-body wanted to be humiliated again after black hawk down
c) its africa so it aint worth it and wouldn't commit

Otherwise exactly right...the UN Can NOT go in unless the nation has asked for that and then the remit is very narrow so the soldiers often have to stand by and watch heinous things happen and have limited effect.