From First Read:

Per NBC’s Andrea Mitchell, officials say it was U.S. intelligence that learned of the secret plant more than a year ago — before President Obama’s election; Israel also knew about it, too. They most likely would not have gone public if Iran had not discovered that the U.S. was onto them and had it not notified the U.N.’s international inspection agency on Monday. By the way, Mitchell adds, the site is 30 kilometers outside of Qum, Iran’s holy city. That means that any military strike would be very difficult politically, because it would around huge reaction throughout the Muslim world. Also today, watch for Russian and Chinese reaction. Yes, they were notified of our intelligence this week, but their reaction is unknown.