Turtles.

This is coolbert:

From Russia with love! Torpedo los! Thousands of them.

"The trend that is now emerging ins switching from heavy to light torpedoes. IN terms of weight, this means moving from two ton weapons to 35-40 kg ones. That's fantastic and it is an essentially different conception."
 
"When there is only one large enemy target, neutralizing it is difficult but possible. But if there are thousands of 'combat turtles' and you don't know which are real and which are just an imitation, it is a much more difficult"

"TINY RUSSIAN TORPEDOES"

Thanks to WIZARD through Harry at Sharkhunters:

"The Russian defense industry has embraced a new trend in manufacturing torpedoes; the development of a mini-torpedo with artificial intelligence. A mini-torpedo is expected to have a weight of up to 40 kilo-grams [88 pounds] and its main combat advantages is that such weapons are silent running and wake less"

". . . A turtle-type torpedo moves at very low speeds (2-3) miles per hour, but generates almost no noise and wake."

A swarm! NO wake! NO noise! Love that image too! 

coolbert.