sentences:  Israel is a participant in the F-35 Lightning II fighter development program and was offered access to the F-22 Raptor program, though it turned this down due to the high costs.The U.S. and Israel also cooperate jointly on a number of technology development programs, notably the Arrow missile system and the Tactical High Energy Laser (also known as Nautilus).The two countries carry out regular exercises together, including carrying out biennial exercises codenamed Juniper Cobra intended to test interoperability between the two militaries.