Underwater Encounters

I get this email from the Navy's Secret Network, SIPRNet.

And it's from my boss's operations officer.

I was reporting to a four-star Admiral, U.S. Fleet Forces Command.
His operations officer was a two-star, and the email was sent to all the subordinate commanders.

This is at least 20 flags and SESs.

All the deputies are copied on it, and the title of it is Urgent Safety of Flight Issue. All caps.

The body of the email said, if any of you know what these are, tell me ASAP.
We are having numerous near-mid-air collisions, and if we don't stop it, we're going to have to cancel the exercise.