No actual proof of that. The "evidence" is the speculation that an Iraqi military that fought Iran to a draw and that dubya stupidly disbanded couldn't figure out WW II era explosive technology that was first used in oil fields even though Iraq's main export was oil.
Iran back in 2013 tried to make peace with the U.S. They went for the same deal that Bush gave Ghaddafi and that Obama later renigged on. We have a common enemy in Saudi backed Wahabi extremists. Instead John Bolton, the same John Bolton that Trump stupidly brought into his inner circle and that later gave aid and comfort to Adam Schiff, is the one who killed the Lawrence Wilkerson / Iran peace initiative. I personally believe the strike was a move by Trump to appease John Bolton to keep him from testifying. There is absolutely no reason for the United States to be on a war footing with Iran. None whatsoever. Justin Amash, Mike Lee and Rand Paul all agree on this.