Note on cost basis: All USD amounts from US government sources (GAO, CBO, DoD) in this article are expressed in Base Year 2012 Dollars (BY2012$). Adjusted for inflation to 2026, actual values are approximately 40–50% higher.
The Block 4 modernization originally comprised 66 new capabilities but has been reduced due to massive delays and cost overruns [43]:
| Parameter | Originally planned | Current status (2025) |
|---|---|---|
| Completion | 2026 | 2031+ |
| Cost | ~12 billion USD | ~18+ billion USD (+6 billion over budget) |
| Capabilities | 66 | Reduced to a "subset" |
Source: GAO-25-107632 [43]
TR-3 replaces the legacy Integrated Core Processor (ICP) with a new system featuring [35]:
Chronology of Delays:
ALIS (Autonomic Logistics Information System) was the original maintenance information system of the F-35, plagued by severe problems [45]:
ODIN (Operational Data Integrated Network) replaces ALIS as a cloud-based system [45]:
Already in planning as the successor to Block 4 modernization with additional capability enhancements [46].
[24] Defense News: Key tests for latest F-35s will begin in 2026. 2025
[35] Lockheed Martin / F35.com: Block 4 Capabilities
[43] GAO-25-107632: F-35 JSF: Actions Needed to Address Late Deliveries (PDF). 2025
[44] Defense Security Monitor: A Sobering Report on the DoD's Largest Weapons Program. 2025
[45] Air & Space Forces Magazine: F-35 Program Dumps ALIS for ODIN
[46] Air & Space Forces Magazine: First F-35 Block 4 Updates, Block 5. 2025