Highly-enriched uranium held in Iran sites hit by U.S. strikes

NBC News' Richard Engel explains what operations take place in the three nuclear sites in Iran that have been hit by U.S. strikes. For more context and news coverage of the most important stories of our day, click here: https://www.nbcnews.com » Subscribe to NBC News: http://nbcnews.to/SubscribeToNBC » Watch more NBC video: http://bit.ly ...