Weird creature with wings seen over Alexandria, Virginia

On February 12, 2018, a person living in Alexandria, Virginia, saw a strange brownish UFO looking like an aquatic mammal with wings. Is it a weird creature or an alien spacecraft?

Witness statement:

Observed from my 15th floor condo 4 miles from Pentagon a large object in the West sky on February 12th at 6pm. It looked like a large aquatic like mammal with flippers or wings, dark in color slowly rotating in the sky. It rotated to the side facing in the direction of the Pentagon. When I took pictures I captured about 7 or 8 glowing white objects that took on different shapes and separated. Not sure how long show lasted, probably about two hours because I stopped watching.

Source, 14th February 2018