Army Gen. Paul Nakasone, who leads the National Security Agency and U.S. Cyber Command, testifies on Capitol Hill in January. Nakasone has been calling for the U.S. to take a harder line against rivals in cyberspace. He said the U.S. sent three Cyber Command teams to Europe last November as part of a larger effort to prevent Russian interference in mid-term elections.

Army Gen. Paul Nakasone, who leads the National Security Agency and U.S. Cyber Command, testifies on Capitol Hill in January. Nakasone has been calling for the U.S. to take a harder line against rivals in cyberspace. He said the U.S. sent three Cyber Command teams to Europe last November as part of a larger effort to prevent Russian interference in mid-term elections.