The "Red Team" is the Pentagon term for the officers who play the enemy in Department of Defense wargames. Most of the time, the Red Team is just officers assigned to that chore for a particular exercise and the enemy is played pretty much as if it were an American force (although not with American capabilities, just to maintain some shred of realism.) For decades, the few who knew better, and got assigned to  "Red Team" duty,  actually ran the enemy side of things the way the enemy would. This was not popular with the brass, as it often produced unpredictable results. Now the Pentagon as, again, ordered the armed forces to use honest Red Teams. The new, permanent Red Teams will be responsible for assuring that future wargames they participate in;

Challenge all assumptions
Make worst-case projections
Assess risks and vulnerabilities
Look into emerging threats and capabilities

In addition, the new Red Teams will be responsible for designing wargame scenarios and develop opposing forces and plans, right up to the political and policy level.

While there are plenty of officers qualified, and willing to do this kind of work, there is not a lot of enthusiasm for top flight Red Teams among Pentagon generals and admirals. The reason for this is, and always has been, the ability of a good Red Team to win. If that happens, the brass that developed American plan is embarrassed. Generals do not like to be embarrassed, especially in public. They do not like to see their carefully prepared plans torn to shreds by a bunch of wise guys pretending to be the leaders of some third rate foreign army. While we all acknowledge that "trail and error" is a perfectly respectable, we live in an age where "zero tolerance" is the mantra of government bureaucrats (in or out of uniform.)It's considered bad form to even fail during a practice. This is stupid, but we're dealing with a bureaucracy here. The Red Teams, naturally, consider themselves a failure if they don't break their opponents carefully constructed plan. While logic says the Red Team should have a shot at victory, bureaucratic reality pulls the situation to the other direction.