Meta is restricting the use of the upside-down red triangle emoji, a reference to Hamas combat operations that has become a broader symbol of Palestinian resistance, on its Facebook and Instagram, and WhatsApp platforms, according to internal content moderation materials reviewed by The Intercept.

Since the beginning of the Israeli assault on Gaza, Hamas has regularly released footage of its successful strikes on Israeli military positions with red triangles superimposed above targeted soldiers and armor. Since last fall, use of the red triangle emoji has expanded online, becoming a widely used icon for people expressing pro-Palestinian or anti-Israeli sentiment. Social media users have included the shape in their posts, usernames, and profiles as a badge of solidarity and protest.

The symbol has become common enough that the Israeli military has used it as shorthand in its own propaganda: In November, Al Jazeera reported on an Israeli military video that warned “Our triangle is stronger than yours, Abu Obeida,” addressing Hamas’s spokesperson.