Facebook COO Sheryl Sandberg and Twitter CEO Jack Dorsey are in the room and testifying before the Senate Intelligence Committee, but Google declined to send a senior executive.

Committee chairman Sen. Richard Burr said the committee would have “valued the opportunity to speak with them [Google] at the appropriate level of corporate representation.”

“I’m deeply disappointed that Google — one of the most influential digital platforms in the world — chose not to send its own top corporate leadership to engage this committee,” Sen. Mark Warner, the committee’s top Democrat, said.

He added that there are “structural vulnerabilities” in multiple Google products, including Google search, YouTube and Gmail, about which members of the committee want answers. “Google has an immense responsibility in this space,” he said.