As my friend Mike Fredenberg says in his recent National Review article (see link below), the F-35 is a procurement mess that should be cancelled. The Pentagon would have you believe that there is no alternative to the F-35. Actually there are two alternatives. The F-15SE Silent Eagle and the F-18 Advanced Super Hornet are both possible replacements for the F-35. The F-15SE was originally proposed as an exportable stealth aircraft for foreign sales to countries who weren't approved to buy the F-35. It's got stealthy characteristics, much better weapons payload, better electronics and costs about 2/3 of what an F-35 costs. I believe the development on this airplane wouldn't take much time, since most of the design work is already done and it's based on a currently deployed design. The Israeli Air Force wanted to buy the F-15SE, but they were denied an export license for it. The Pentagon forced the IAF to buy the F-35 instead. Trump's tweet on developing a stealth version of the navy's F-18 is also possible. A reduced radar cross section F-18 Advanced Super Hornet has been proposed, which might be why Trump mentioned it in his tweet. The way to stop procurement train wrecks like the F-35 is to cancel them and buy something else.
Articles on F-15SE Silent Eagle:
Article on the F-18 Advanced Super Hornet:
My post on military procurement: