Citing the company’s “failure to provide answers to important questions,” Sens. Elizabeth Warren, D-Mass., and Bernie Sanders, I-Vt., are pressing Meta, which owns Facebook and Instagram, to respond to reports of disproportionate censorship around the Israeli war on Gaza.

“Meta insists that there’s been no discrimination against Palestinian-related content on their platforms, but at the same time, is refusing to provide us with any evidence or data to support that claim,” Warren told The Intercept. “If its ad-hoc changes and removal of millions of posts didn’t discriminate against Palestinian-related content, then what’s Meta hiding?”

The letter was written following widespread reporting in The Intercept and other outlets that detailed how posts on Meta platforms that are sympathetic to Palestinians, or merely depicting the destruction in Gaza, are routinely removed or hidden without explanation.