As the F-35 Joint Program Office continues to refine its strategy for follow-on development, the Senate Armed Services Committee is concerned about the cost to upgrade older jets to the most modern configuration and is proposing more than $88 million in its mark of fiscal year 2019 defense policy legislation to support fleet retrofits. In a report to Congress earlier this year, the JPO estimated it would cost approximately $16 million per jet to upgrade older-model F-35s -- those purchased...