According to the sources familiar with Nunes’ letter, it asks FBI Director James Comey to investigate and report back to the intelligence committee on the circumstances behind the leaking of details from Trump’s phone calls with foreign leaders, as well as from communications between his former National Security Adviser Mike Flynn and the Russian Ambassador to the U.S.

Nunes’s letter also asks Comey to look into leaks related to the Central Intelligence Agency’s rejection of an elite-level security clearance for one of Flynn’s closest deputies on the National Security Council, senior director for Africa Robin Townley.

It’s unclear if Nunes’s letter asks the FBI to investigate other leaks as well, and the California congressman’s office did not comment. Neither did Townley, the FBI or the CIA.