Forces News has been given special access to the US Air Force squadrons giving American and allied pilots "the hardest challenge they'll probably ever face".
64th and 65th Aggressor Squadron, based at Nellis Air Force Base in Nevada, are the US Air Force's 'enemy' squadrons.
Their mantra is 'learn, teach, replicate' and they provide realistic air threats for training pilots by acting like adversaries.
Inside their buildings, it is extremely different from anything else.
Communism symbols can be seen and Lieutenant Colonel Don Davenport, Director of Operations 64th Aggressor Squadron, told Forces News the role as enemy on an exercise starts as soon as you walk through the door.
"You're putting on your red patch and you're becoming the red adversary," he said, "which is to go out, learn the threat, replicate the threat, teach the threat."
"We're bringing our A game at all times."
Forces News joined the squadrons Exercise Red Flag 23-1 – the biggest Allied air exercise ever, involving US, UK and Australian personnel, which aimed to ensure they are prepared for the threat posed by China.
In one scenario, the squadrons – the red force – were tasked with disrupting an 'offensive' mission by the blue force – the good guys.
The 'fight' area is designated just off the coast of Mexico, in international waters – with this iteration of the exercise being partly conducted over the ocean for the first time.
This means the pilots must be prepared to land in water – wearing a layer of skin-tight rubber under their flight suits.
Pilots use a vacuum cleaner to suck all the air out of the suits before climbing into the cockpit to ensure they are completely sealed in with no air bubbles.
In another scenario on the exercise, the blue 'friendly' force was tasked with escorting a B-52 bomber to the weapon launch line and ensuring it survives engagement with the red force, the 'baddies'.
The red force then attempts to shoot down the B-52 and the escort fighter jets.
The enemy force fly F-16s – capable of air-to-air and air-to-ground fighting and capable of travelling at twice the speed of sound.
Each time they are "shot down", they head for the regeneration line, tagging the line and coming back to simulate the enemy sending up more forces.
Lieutenant Colonel Brandon Nauta, Commander 65th Aggressor Squadron, told Forces News it is important pilots understand both sides of the fight.
"You have to not only understand the tactics and procedures that we would fly if we were on the good guy side.
"But we also have to understand the tactics and techniques that an adversarial pilot or a unit would use."
Lt Col Davenport added that the air force teams "have to stay in the books, especially with the changing threat that's going on around the world".
He also said each member of the exercise, who has an individual level of expertise, is gaining valuable experience.
"So it's not just on the one individual to go out and try and figure everything out," he said.
"It's a collective team that is going out and studying what is happening in the world."