Lockheed Martin and U.S. Air Force Complete Mk21A Flight Test

Lockheed Martin and the U.S. Air Force completed a flight test of an unarmed developmental Mk21A re-entry vehicle on November 5, 2026. The reported test launched from Vandenberg Space Force Base and flew over the Pacific Ocean.

Key details

• The Mk21A is in development as the re-entry vehicle for the Air Force’s planned Sentinel intercontinental ballistic missile system.
• Its design updates the existing Mk21 and is intended to carry the W87-1 warhead.
• Lockheed Martin said test data will inform design changes and later tests.
• The program is moving toward a system-level Critical Design Review, a formal assessment of design maturity.
• The flight demonstration took place under a prime military contract reported to be valued at more than $1 billion.

The flight test used an unarmed developmental Mk21A re-entry vehicle.

Why it matters

The Mk21A forms the payload-carrying front end of the planned Sentinel system. Test data will contribute to design refinement and subsequent trials before the program’s system-level design review.