Tanks in Beijing have left the impression that they’re aimed at the reporters themselves:

“The move, which was imposed over the heads of the Beijing Olympic Committee, was a vivid illustration of the continuing power of the Communist Party even as the country has been opened to unprecedented from the outside world.
It followed a letter sent to the editors of all newspapers in the country containing 21 rules for reporting during the Olympics.
The letter, leaked to The Daily Telegraph, lays particular stress on anything to do with foreigners and is clearly aimed at preventing any events that undermine the show of national unity that has surrounded the Games being released to the general public.
The armoured personnel carriers, unprecedented at recent Games, were stationed at either end of the main press centre, one of a number of increased security measures put in place around Beijing. Armed police stood with sub-machine guns in key areas, including at the press centre entrances.”