Was in DC at the end of September staying at the Waldorf (Trump’s old hotel), and saw a bunch of black SUVs with this flag in the windshield parked on the curb by an entrance not open to regular traffic. Also saw press there and some folks walking around in military uniforms. An image search suggested it might be Gabon, but that flag didn’t include the seal in the middle.
If you google “coat of arms of gabon” you get the coat of arm you see in the middle of the flag. Guess some vips from gabon are in town.