Modern submarines are stealthy and heavily armed with an array of weapons, including missiles, torpedoes and mines. They are able to strike targets on the surface, on land or even—in the not too distant future—in the air. Countering their impact requires a sophisticated capability including the integration of a range of sensors, weapons and countermeasures. This report reviews the current state of our anti-Submarine warfare capability and makes a series of recommendations for making good the shortfalls. With around $10 billion of ship building and helicopter projects to be decided upon in the next twelve months, this is the time to make decisions about what systems pursue.