Read this: The original NAS Bermuda on the west side of the island, a seaplane base until the mid-1960s, was designated as the Naval Air Station Bermuda Annex. It provided optional anchorage and/or dockage facilities for transiting US Navy, US Coast Guard and NATO vessels, depending on size. An additional US Navy compound known as Naval Facility Bermuda (NAVFAC Bermuda), a SOSUS station, was located to the west of the Annex near a Canadian Forces communications facility. Although leased for 99 years, US forces withdrew in 1995, as part of the wave of base closures following the end of the Cold War.

What did US forces do in 1999?
What is the answer? (If it cannot be answered, return "unanswerable")
unanswerable