The US Army sharply restricts public access to Fort Belvoir, one of its installations about 12 miles south of the Pentagon. After being an open post for over 25 years, Belvoir has now erected barriers across many of the roads leading into it, leaving only six guarded gates as points of entry and exit. Twenty access points are being permanently closed. Visitors must now register their vehicles at a visitor’s center or get a day pass to enter the base. [MDW News Service, 7/2001; Washington Post, 8/15/2001] The access restrictions will allow commanders to know who is entering the base 24 hours a day and adjust security measures immediately if needed. [MDW News Service, 8/3/2001] All other Military District of Washington (MDW) installations are implementing similar changes, due to Army concerns about terrorism (see August 15, 2001). Fort Belvoir has about 20,000 workers and is home to many different agencies, including the US Army Intelligence and Security Command (INSCOM), plus the headquarters of the Defense Logistics Agency and the Defense Technical Information Service. [Military District of Washington, 8/2000; Washington Post, 8/15/2001; GlobalSecurity (.org), 10/21/2001] Occupying over 500 acres at Belvoir is Davison Army Airfield. The 12th Aviation Battalion, which is MDW’s aviation-support unit, is stationed at Davison. This operates UH1 “Huey” and UH60 Black Hawk helicopters in support of training and “contingencies” for various MDW units. [Military District of Washington, 8/2000; GlobalSecurity (.org), 1/5/2002] The Washington Post has reported, “Fort Belvoir will be holding exercises the next two Tuesdays to test the changes” in access to the base. [Washington Post, 8/15/2001] This will therefore include September 11 (a Tuesday). Other reports will confirm an antiterrorism exercise being conducted at Belvoir on 9/11 (see 8:30 a.m. September 11, 2001).