From the U.S..Naval Proceedings Web site:

ARLINGTON, Va. - The U.S. Navy submarine force is creating an aggressor squadron as one initiative to ensure all subs are combat-ready as the service trains to take on China and Russia, the commander of Naval Submarine Forces said on Wednesday.
Vice Adm. Charles Richard, who took command in August, drew attention during the change of command ceremony by telling the force to "prepare for battle."
He has backed up those words with actions in the months since, moving ahead with a plan - updated in March to reflect the National Defense Strategy - that includes refocusing training and certification on combat and developing new tools and concepts to support high-end warfighting.
The plan - called the Commander's Intent for the United States Submarine Force and Supporting Organizations - led to an overhaul of training for the attack submarine force, Richard said today while addressing the Naval Submarine League at its annual conference.
"We have restructured and retuned the fast attack training period to ensure that we're ready for that high-end fight, including restructuring what we used to call the Tactical Readiness Evaluation, and it is now a Combat Readiness Evaluation to ensure we're focused on warfighting," he said.