The data transfer capabilities available in the fifth-generation F-35 are unique to the F-35. The F-35 is interoperable with fourth-generation capabilities, understanding the limitations of that lesser interoperability. But in order to remain fully interoperable and operationally relevant with our key allies for the mid and far future, we must have the types of technologies that are available only through the fifth-generation F-35.
On October 28th, 2010. See this statement in context.