Not at all.

First it’s a common mistake to assume that the F-35 and the F-15 are interchangeable. Below is a picture of a loaded F-15. No it’s not stealthy, but it carries 29,500 lbs. Even if an F-35 sacrifices its stealth and carries weapons externally, it’s limited to 22,000 lbs (5700 lbs internal for stealth).

When the F-35 is out of missiles it can either return to base for rearming, or it can share its targetting data to another fighter like the F-15EX so it can shoot at air targets it can’t detect itself, and likely from a distance it is safe from being fired on.

Add to that fact that Lockheed Martin and the rest of the F-35 enterprise was likely maxed out for production of F-35s. The USAF actually bought more F-35s than projected. Since parts are made all over the world, if any one of those suppliers couldn’t continue to ramp up production it would limit the number of complete jets that can be delivered.

There are promised numbers across the other nations buying the F-35, so even with the Turkey buy cancelled, if the US tried to buy more I suspect LM would not be able to deliver on other country’s orders.

Also, when you bring a new airframe into a base, you need to acquire different tools and maintenance support equipment. Because the F-15EX will replace aging F-15s, the infrastructure is largely reusable. This allows us to deliver capabilities without waiting for airfield improvements.

Some have suggested the buy was an attempt to save Boeing from bankruptcy-not unless the AF is clairvoyant. The 737MAX issues were known last year when USAF proposed buying a mix of F-15s and F-35s, but the second punch of COVID was not known when the AF leaders testified in support of the President’s budget.

In other words, buying F-15s allows us to replace aging F-15Cs faster than waiting for F-35s while delaying additional costs that would be required if we could get more F-35s faster.