What actor never served in the military but is recognized for his portrayal of a military lieutenant, frequently performs on USO tours at military bases around the world, and is one of the few people to fly in a U-2 spy plane up to 70,000 feet?

What actor never served in the military but is recognized for his portrayal of a military lieutenant, frequently performs on USO tours at military bases around the world, and is one of the few people to fly in a U-2 spy plane up to 70,000 feet?