The American Medical Association said the Pentagon’s recent evaluation of the requirements to accommodate transgender personnel “mischaracterized and rejected the wide body of peer-reviewed research on the effectiveness of transgender medical care.”

The letter from CEO James Madara, first obtained by POLITICO, also slams the suggestion that the cost of providing medical care to transgender troops should be a reason to keep them out of the military.

“The financial cost is negligible and a rounding error in the defense budget,” Madara writes. “It should not be used as a reason to deny patriotic Americans an opportunity to serve their country. We should be honoring their service.”

A 2016 study conducted by the government-funded RAND Corporation estimated nearly 4,000 transgender troops are serving on active duty and in the reserves. Advocacy groups estimate the number is much higher, around 15,000.

The RAND study also estimated paying for the transition-related healthcare of transgender troops would cost between $2.4 million and $8.4 million each year, a less-than-1 percent increase in active-duty healthcare costs.

The Trump administration announced in March that it will follow through on the president’s controversial pledge to ban transgender troops from serving, but left many of the implementation details up to Mattis. The retired Marine general said in his recommendation to Trump that most transgender people who have been diagnosed with gender dysphoria — including those who required medical treatment or surgery — will be disqualified to serve in the military.

But the AMA strongly disputes the rationale being used.

“We believe there is no medically valid reason — including a diagnosis of gender dysphoria — to exclude transgender individuals from military service,” it says. “Transgender individuals have served, and continue to serve, our country with honor, and we believe they should be allowed to continue doing so.”

Several federal courts have issued temporary injunctions, preventing the Trump administration from implementing the ban until the courts rule on whether it is unconstitutional to bar a group of people from serving based on their gender identity.