An emotional Jimmy Kimmel returned to the airwaves last night after ABC indefinitely suspended his show following Federal Communications Commission Chair Brendan Carr’s threats to revoke the broadcast licenses of affiliates over comments Kimmel made about Charlie Kirk’s assassin. In his monologue, Kimmel spoke about how foreign comedians look to the U.S.

Jimmy Kimmel: “They know how lucky we are here. Our freedom to speak is what they admire most about this country. And that’s something I’m embarrassed to say I took for granted until they pulled my friend Stephen off the air and tried to coerce the affiliates who run our show in the cities that you live in to take my show off the air. That’s not legal. That’s not American. That is un-American. And it is so dangerous.”

President Trump also suggested that he might sue ABC after Kimmel returned to the airwaves, saying, “We’re going to test ABC out on this.” It comes after ABC settled a civil defamation suit with Trump for $16 million last year.

Meanwhile, Senators Elizabeth Warren, Ron Wyden, Ed Markey and Chris Van Hollen have announced an investigation into Nexstar and Sinclair, major TV station owners that account for roughly 70 ABC affiliates across the U.S., who are refusing to air “Jimmy Kimmel Live!”

In a letter addressed to the leadership of Nexstar and Sinclair, the senators write, “If you suspended a late-night comedian’s show in part to seek regulatory favors from the administration, you have not only assisted the administration in eroding First Amendment freedoms but also create the appearance of a possible quid-pro-quo arrangement that could implicate federal anti-corruption laws.”

Nexstar is currently seeking FCC approval for its $6.2 billion merger with Tegna, while Sinclair is also exploring a possible merger for its broadcast business.