Electrical motive parts businesses are growing and remain a profitable business, according to data released Friday by the U.S. Department of Energy.

But demand for parts and labor in the electric drivetrain market has fallen sharply since the U,S.

Energy Department announced last year it was buying the components from China for $3.5 billion.

The Department of Defense plans to build its own electric drivetrains for the Army, but the cost has become a point of contention between Congress and the Pentagon.

The Pentagon wants to purchase the entire range of parts for the fleet of F-35 Joint Strike Fighters, but Democrats and some Republicans are calling for a shorter period of time.