Donald Trump isn’t going to like this one at all.

Defense Secretary Mattis basically just gave Trump the middle finger on his anti-transgender policy edict regarding military service.

Mattis freezes transgender policy; allows troops to continue serving, pending study

WASHINGTON — Defense Secretary Jim Mattis late Tuesday announced that transgender troops will be allowed to continue serving in the military pending the results of a study by experts.

The announcement follows an order from President Trump — first announced in a tweet — declaring that transgender service members can no longer serve in the military, effectively reversing an Obama administration policy. The order also affects the Department of Homeland Security, which houses the Coast Guard.

“Once the panel reports its recommendations and following my consultation with the secretary of Homeland Security, I will provide my advice to the president concerning implementation of his policy direction,” Mattis said in the statement. “In the interim, current policy with respect to currently serving members will remain in place.”