-- A national debate about race and proper military behavior broke out this week after sixteen African-American West Point cadets posed with raised fists for a pre-graduation picture.
He did say the cadets showed "a lapse of awareness in how symbols and gestures can be misinterpreted and cause division."
The gesture has a long history as a symbol of defiance and solidarity. Athletes have sometimes used a clenched-fist gesture as a political statement.
Here's a closer look at the gesture.
Who Else in History Used a Clenched-Fist?
The gesture has a long history as a symbol of defiance and is often associated with both left-wing politics as well as oppressed groups.
In the 1960s, the black power movement used it as a gesture to represent the struggle for civil rights. The Black Panther Party used it as a symbol of resistance.
In one iconic image, American sprinters Tommie Smith and John Carlos raised their fists during a medal ceremony at the 1968 Mexico City Olympic Games. Later, in an autobiography, Smith said he saw it as a "human rights salute."
Is the Clenched-Fist a Political Statement?
Sometimes a fist raised in the air is simply a fist raised in the air, even when political figures use the gesture.
Sanders has often responded to the crowd and shows his fist as if to say “fight the good fight” and often does it when he appears on stage to show solidarity with the crowd.
How Does the Clenched-Fist Relate to the Black Lives Matter Movement?
While raised fists have frequently appeared in the Black Lives Matter movement, it isn't the only symbol used.
Defenders of the West Point cadets have said the women were celebrating their impending graduation, not trying to make a political statement.