We have just had a visit by a NATO patrol group - four ships from four different countries under a British commander.  It is impressive how closely multiple navies are working together on a routine basis. Greek and Turkish ships, for example, were operating side by side in this patrol. And when those same ships serve on anti-piracy duty off the Horn of Africa, they team up with navies from across the globe in a common effort.    The Rear Admiral commanding the patrol met with the head of the Tunisian Navy. His message here, as elsewhere, was "Dare to share!" These days sharing information on security issues is the key to staying ahead of the ever-evolving threats.