For months now, internet pundits and lawmakers alike have debated the logic behind the Pentagon-directed United States Air Force (USAF) initiative to procure new F-15s from Boeing. In an era of stealth fighters like the F-35 Joint Strike Fighter and F-22 Raptor, many people would argue that purchasing new “old” fourth-generation fighters is a step in the wrong direction.

Those in favor of the purchase, however, contend that the F-35 is still riddled with issues and exorbitantly expensive to operate, thus making the lower-cost F-15s the right answer for missions in uncontested air space. Which, it pays to note, is where most ongoing combat operations take place today.

In the battle over fighter jet perceptions, Lockheed Martin locked horns with the low-cost concept behind the F-15EX procurement from Boeing, and lawmakers with large portions of F-35 production in their respective states joined the fight. They’ve called on U.S. President Trump and other senior government officials to take the money earmarked for new F-15s and throw it into the F-35 pot to maximize fifth-generation fighter procurement.

However, the USAF responded to those calls by breaking its fighter procurement strategy into basic arithmetic: it requires more new fighters per year than it can afford in terms of F-35 production, so an alternative needed to be found.