For four successive years, Congress has rejected administration proposals to terminate the program to develop the General Electric/Rolls-Royce F136 engine as an alternative to the Pratt & Whitney F135 engine that currently powers the F-35 Joint Strike Fighter (JSF). The administration's FY2011 budget submission again proposes to terminate the program. The alternate engine program began in FY1996, when defense authorization conferees directed the Department of Defense (DOD) to ensure that the JSF (then "JAST") program "provides for adequate engine competition." Through FY2009, Congress has provided approximately $2.5 billion for the Joint Strike Fighter alternate engine program. The program is projected to need an additional $1.9 billion-2.9 billion through 2017 to complete the development of the F136 engine. Critics of the proposal to terminate the F136 alternate engine argue that termination was driven more by immediate budget pressures on the department than the long-term pros and cons of the F136 program. They argue that engine competition on the F-15 and F-16 programs saved money and resulted in greater reliability. Some who applaud the proposed termination say that single source engine production contracts have been the norm, not the exception. Long-term engine affordability, they claim, is best achieved by procuring engines through multiyear contracts from a single source.