Closed session

In the Congress of the United States, a closed session (formally a session with closed doors) is a parliamentary procedure for the Senate or the House of Representatives to discuss matters requiring secrecy.

The discussions which take place in a closed session are subject to confidentiality rules and are similar to an executive session, which itself can be open or closed. An executive session is for business which includes the President of the United States.

The United States Senate has been called into closed session 54 times since 1929.

Under the Standing Rules of the Senate, a closed session may be called by any Senator through a simple motion. Once the motion is seconded, the presiding officer of the Senate directs the Capitol Police to clear the public galleries of spectators, and close all doors of the chamber. The Senate floor will be cleared of all persons except the Senators and listed parliamentary officers, including the Secretary, the Sergeant at Arms, the Parliamentarian, and certain clerks. These officers are sworn to secrecy. All sitting Senators present are called to the floor, and they must surrender any electronic communications equipment including mobile phones and other electronic devices.

...
Wikipedia