The limits of national control over modern defence supply chains

How vulnerable is Western equipment to the United States withholding support?

The risk is real, but supply chains are interdependent and neither American nor European systems are fully autonomous.

Governments can diversify suppliers and sustain domestic industry, but few modern weapons are wholly national. The F-35 contains European components and Eurofighter uses American ones, so political disruption on either side of the Atlantic can still affect readiness. Maintaining both aircraft families spreads some risk but cannot create complete autonomy when their supply chains cross borders. The flag attached to a weapons program does not by itself reveal who controls every critical component.