A naval blockade is an act of war, but U.S. ships would not fire on ships attempting to run it, says Mark Norman, a retired Royal Canadian Navy vice-admiral and fellow with the Canadian Global Affairs Institute. The mission would be to intercept and interdict, order them to stop, possibly using warning shots. Boarding and seizing ships would involve dropping troops by helicopter. 'That gets pretty dicey,' Norman said. »»» Subscribe to CBC News to watch more videos: http://bit.ly/1RreYWS For