The YF-4 Lightning, also known as the VF-X-4, was the prototype of the VF-4 Lightning Advanced Veritech Fighter. It had been a concept since at least 2014, but did not actually see creation until 2015. Some source suggest that the vehicle was abandoned due to cost, while others suggest that different models of the vehicle could still be in use through the Second Robotech War and up to the start of the Third Robotech War in 2031, although in limited numbers.