The Pentagon will shut its doors Monday to all unofficial visitors, and restrict entry for international travelers and large groups, the latest in a series of significant restrictions on military personnel and access to U.S. bases and installations.

On Friday night, the Defense Department issued a statement outlining several rules designed to limit the spread of COVID-19, or the coronavirus virus. Among them, all international travelers will not be allowed into the massive building before a 14-day waiting period after their return to the United States. Retirement and promotion ceremonies -- a regular occurance at the military’s official headquarters -- also will be halted.

Foreign delegations will be considered “on a case-by-case basis” by senior leaders.

Earlier in the week the Pentagon ceased public tours.

At 3.7 million square feet, the Pentagon is the enormous headquarters of the U.S. military, in Arlington, Va. It is also the terminus of a large metro bus system that carries thousands of Washington-area commuters to and from the Pentagon’s metro rail station. Completed in 1943, the Pentagon now houses more than 25,000 workers and sees about 100,000 visitors each year and has three times the floor space of the Empire State Building. It’s one of the few military installations that hold more officers than enlisted men and women, and is a no-saluting zone.

The restriction extends to other Washington-area office buildings, “including the Mark Center, Defense Health Headquarters, U.S. Court of Appeals for the Armed Forces, and DOD leased facilities.”

The full statement is below:

Effective midnight on Sunday, March 15, 2020:

. All unofficial visits are suspended, to include personal guests and friends of DOD personnel and contractors. All large gatherings, such as retirement and promotion ceremonies, shall cease. All Pentagon Tours have been suspended since March 12, 2020.

. All official visits by international partners and visitors are suspended. Exceptions will be considered on a case-by-case basis by the Secretary of Defense, Deputy Secretary of Defense, Chief Management Officer (on behalf of the Fourth Estate), Director of the Joint Staff, as delegated by the Chairman of the Joint Chiefs of Staff, and the Secretaries of the military services.

. Any individual, DOD civilian, military service member, contractor, or official visitor with recent international travel may not enter the Pentagon Facilities within 14 days from the date of their arrival back to the United States. Access may be restored on the 15th day, if the individual remains asymptomatic.

. Sponsoring offices for visits to the Pentagon building, Mark Center, Defense Health Headquarters, U.S. Court of Appeals for the Armed Forces and other Pentagon facilities must register official visitors at least 24 hours in advance through the Pentagon Force Protection Agency Visitor Management System. Official visits to DOD leased facilities will be managed by the designated officials or security managers.