Last week, Air Force secretary Heather Wilson released a report indicating that the establishment of a new branch of the American Armed Forces tasked specifically with space defense would cost an estimated $13 billion over five years — a figure that was widely touted throughout the media as a sign that the Trump-led initiative is too expensive to be worthy of pursuit. Of course, within the defense community there’s no question that space defense is a necessity for the national security enterprise, and many even argued that $13 billion is not all that substantial a number when compared to other defense efforts like the construction of the first Ford class aircraft carrier (which promises to exceed $13 billion itself) or the F-35 program that will likely exceed $1.5 trillion over its lifespan.

However, thorough analysis of the Air Force estimate conducted by the defense budget analysis arm of the Center for Strategic and International Studies has revealed a number of issues with that oft-touted $13 billion figure, according to the center’s budget director, Todd Harrison. The estimate was supposed to project overall costs of establishing the new force and sustaining it over the span of five years, but the figures used to create that estimate included vastly exaggerated personnel costs and construction projects no one seems to be able to adequately justify.

Heather Wilson called the Air Force’s figures “conservative” when making the media rounds, but Harrison argues that they included the employment of thousands of personnel that may not be needed — and worse, the estimate was built on the assumption that the average per-person compensation rate for Space Force personnel would be $175,000 per year. Most salary analysis websites, however, list the average military salary at somewhere between $30,000 and $60,000 per year.

Heather Wilson argued that the Space Force would force the Pentagon to employ some 13,000 additional troops, though Harrison argued that the number of troops required for space efforts within the Air Force would drop at a commensurate rate to the increase in the Space Force (as the Air Force currently manages that area of responsibility). Personnel increases may ultimately be required, but there’s no strong evidence to suggest those increases would amount to some 13,000 people. That means the Air Force estimate may be off by as much as $1.5 billion per year. In other words, the Air Force may have exaggerated the costs of standing up a Space Force by more than doubling it.