From Wikipedia (redacted):
"From 1989 to 2004, the South Dakota Air and Space Museum located on the grounds of Ellsworth Air Force Base displayed the 10-short-ton ”Honda-Stealth”, a 60% scale mock-up of a stealthy bomber which had been built by Honda in 1988 for an advertising campaign.
Although not an actual replica of a B-2, the mock-up was close enough to the B-2’s design to arouse suspicion that Honda had intercepted classified, top secret information, as the B-2 project was still officially classified in 1988. Honda donated the model to the museum in 1989, on condition that the model be destroyed if it was ever replaced with a different example. In 2005, when the museum received a B-1 Lancer for display (Ellsworth being a B-1 base), the museum destroyed the mock-up.”
Japanese secret B-2 Stealth Bomber 1988 (youtube)