Washington (AFP) - The prestigious West Point military academy has opened an inquiry after 16 black female cadets posed for a photo with fists raised in militant style.

The pose struck by the cadets, dressed in their gray uniforms while standing on the steps of barracks in late April, is seen by some critics as an implicit show of support for the Black Lives Matter movement and thus a potential violation of a Defense Department rule against "partisan political activity."

West Point seeks to portray itself as a melting pot that brings together talented students from across the country, without regard for racial or ethnic differences, for elite training as future military leaders.

Lieutenant Colonel Christopher Kasker, a spokesman for the academy in New York state, confirmed that the cadets were members of the current graduating class.

"Academy officials are conducting an inquiry into the matter," he said on Saturday.

The young women were following a longtime tradition at West Point, where soon-to-be graduates each year strike stern and straightlaced poses in historic style much as their predecessors have done for more than a century.

But instead of raising their sabers to the sky, as they did in another photo without controversy, the black student-officers sparked a mini-tempest by raising their fists at a school with a predominantly white and male student population.

Some active-duty officers and army veterans have complained that the pose seemed to violate Pentagon rules on avoiding political activity by paying tribute to the black nationalism of the civil rights-era Black Panthers group or to the militant tone of the present-day Black Lives Matter protests against police abuses.

But others raised their voice in defense of the women, saying that they were more "Beyonce" than "Black Panther."

Mary Tobin, a 2003 graduate of West Point who has talked with some of the students about the photograph, said the raised fists signified only unity and pride at accomplishing something -- surviving the rigors of West Point -- that few people, white or black, have done.