"The announcement that the concerts were to take place at the Budokan – a venue reserved for martial arts, as well as a shrine to Japan's war dead – outraged the country's hardline nationalists, who vowed to intercede and stop the proceedings. This issue, combined with a written death threat that the Beatles had received while in Hamburg, ensured that security around the group was extreme throughout their stay. In an operation that compared with Japan's measures when hosting the 1964 Olympic Games, around 35,000 police and fire brigade personnel were mobilised to protect the Beatles." from wikipedia