Sonar pulse

From Command and Conquer Wiki

The sonar pulse was a one-time sonar discharge that was available to Allied commanders when one of their spies infiltrated a Soviet submarine pen and hacked into the soviet computer navigation systems. The pulse has temporarily revealed all Soviet submarines operating in the combat zone by amplifying their sonar signatures directly from the control centers.

The effect lasted for a short while before Soviet technicians were able to rectify the problem and remove outside feed.