Like Linus waits every Halloween eve in a pumpkin patch for 'the Great Pumpkin" to appear, I suspect these sicko Iranian Mullah's think the great Mahdi will crawl out of a well on Aug 22, signaling the time to start their war. I suspect iran will try to close the shipping lanes, and we suspect they will try, which is why on Aug 21 there won't be a rowboat left in Iran without a hole shot in it.
I just hope it doesn't interfere with the season priemere of "prison break".
Add to your explanation that they think he will come during a time of chaos. They think that if they cause chaos it will induce the hidden mahdi to come.