PORTSMOUTH, N.H. – The ocean off the coast of Maine and New Hampshire will be the scene of a drill that will involve the military and government agencies from the United States and Canada.

About 3,000 people are expected to participate in next week’s training exercise, responding to a mock underwater mine explosion near Portsmouth. The goal is to practice, evaluate and recommend improvements for multiagency responses to maritime security threats. Officials say they’ll have a chance to see what works and what needs polishing when it comes to the two nations’ ability to protect and defend North America.

The exercise will be held June 9-13.