Board Thread:Rebirth: Applications/@comment-24019243-20141016022001/@comment-4869113-20141030135120

Konoha took up the initial action to destroy them, because they challenged the five great nations. I'm also certain it was an agreed decision on whom would destroy their hidden village. The Land of Sky, the country survived, but the hidden village did not.

Secondly, Iwagakure was winning in the war against Konoha. They had no reason to ally with a dead nation to help themselves. And with that, they were said to employ the Akatsuki very frequently in the past secretly. I'm certain they had enough manpower to reject a nation's, whom challenged them in the past and were more than certainly an enemy, assistance.