FORT IRWIN (CBS2) —  As American troops leave Afghanistan, thousands of soldiers in California are aggressively training for their next war… against a military force that’s as big as their own.

The U.S. Army has replicated a province in the Middle East on 1,200 square miles of the Mojave Desert at the national training base in Fort Irwin.

For the past two weeks, day and night, 4,000 soldiers prepare to not only fight criminals, guerrillas, and insurgents, but armies with helicopters, planes, tanks, and cyber technology as advanced as theirs.

It’s called Decisive Action Training.

Soldiers are no longer just worried about pockets of insurgents in small towns.

They must handle a much more complex environment.

“We’re preparing to fight an actual army,” a solider told CBS2’s Stacey Butler.

Another solider said they are training to battle, “A military force that is as big as our military force. Head-to-head. Toe-to-toe.”

As the world faces new challenges in the Middle East, the U.S. Army said they’ll be ready for the next battle.