WE HAVE THE SUB.
They no longer have hostages( or power to enact threats made before( cease to exist for the 19)
Watch the water.
Red October.
I like this angle. I always thought that they were on the hunt for some type of rogue sub. Remember that tidbit about ships and planes hauling ass to the gulf of Mexico some time after the Hawaii incident? And I always also thought that the "missing Argentinian sub" may have been some kind of cover story for a more capable rogue sub from maybe some other country (China/Russia?). If my weird theory is correct, Q is telling us that this rogue sub has been neutralized and whatever "hostages" it threatened have been "released.
I kinda like this theory until I hear otherwise.