The Bird's Nest Olympic statium

A Chinese paramilitary policeman attempts to block photos from being taken of a military parade rehearsal outside Beijing's "Bird's Nest" National Stadium, the site of the upcoming Olympics. China has vowed to step up security for the Games and said that with up to 80 world leaders expected to attend the Aug. 8 opening ceremony, it faces a huge responsibility to defend its own people, Olympic athletes and visiting dignitaries.