The New York Times first identified the whistleblower as a CIA officer, which Reuters has independently confirmed.
Mark Zaid, a Washington lawyer who represents the whistleblower, declined to confirm the identity or occupation of his client.
"Publishing details about the whistleblower will only lead to identification of someone, whether our client or the wrong person, as the whistleblower. This will place this individual in a much more dangerous situation, not only in their professional world but also their possible personal safety," Zaid told Reuters.
A CIA spokesman referred inquiries to the office of the Intelligence Community Inspector General, which did not immediately respond to a request for comment.