The Obama administration’s targeting of journalists and their sources is an assault on the First Amendment, a former National Security Agency official and prominent whistleblower says.

“[R]eporters have shared with me privately that some of their most trusted sources within government are increasingly afraid to speak with them, even off-the-record, for fear that they will be monitored and surveilled,” Thomas Drake, a former senior executive of the National Security Agency and a whistleblower who was prosecuted by the Obama administration, told The Daily Caller in an exclusive interview.

“That’s self-censorship,” he said.