Dear BSM1,
I'am an Iranian. It isn't true that we see war, especially nuclear war, as a requirement for Al Mahdi's hastened return!
We believe that good deeds and thoughts can hasten the return of Imam Mahdi (peace be upon him).
I think that there is a misunderstanding. Indeed, we believe that Imam Al-Mahdi comes, when the earth is filled with the tyranny and evil. The nuclear weapon is a kind of evil and tyranny in our view.
We see the good news of the Mahdi, which is important, but our scholars have become oblivious to the warnings of him as well.
Prophecies are never set in stone, God annuls from the book what he pleases and establishes, but it looks like in all probability, the world civilizations will be destroyed and believers will be a minority - just like occurred to many generations in the past.
The Mahdi the hopeful leader he is, is trying to prevent the warning, but he can't do everything.
They are moving against us, and humans are heedless of this warning as their term is coming and their respite is coming nearer to an end.
I wish the Mahdi will be the mercy and favor of God to most humans as he is meant to be, heck, even perhaps all humans, but it looks like the warned disasters are coming about.
Be sure, were it not for Khomeini rising, and Khamanei protecting and holding, the inhabitants of the earth would have long been destroyed for the oppression would have reached a height and it would be upon God to deliver the believers from their oppressors.
We want to hasten the victory that will be on good terms and we wish delay the catastrophe that will be on bad terms. Generally hastening it will mean it's on good terms, and delaying it will be on bad terms, but when oppressors will do what they do, and looks like it's going that way, we want to delay it, because if we hasten then, the world will be almost all destroyed.
There is a term though, and you oppress believers, and it's upon God to deliver believers from their oppressors and Quran shows exactly how he does that.
God praises waiting for the Mahdi but also condemns the type of waiting disbelievers are doing regarding it, which is not being fearful of the event nor hopeful of it, but just saying "let them bring about it if they are truthful" type waiting.
The Mahdi is the last and hugest trial, and when God sends him out, this will be the biggest message and most important thing they hear, although, the Quran is the last revelation and Nubuwa has been sealed.