Mitsubishi took over the development of Jeep vehicles from 1956 to 1999. All Jeeps within this period are basically Mitsubishi developed vehicles with a Jeep tag.
This is basically a result of the Chrysler-Mitsubishi tie up during those years.
What really happened was in 1953 Jeep introduced the CJ-3B's - and Mitsubishi bought the rights to build them. Mitsubishi kept building the thing until 1998, by which point the Americans had gone through all the generations of the CJ, then the YJ, and just rolled out the new TJ.
...but Jeep has always been an American product.