July 12, 2008 (11 images)

Chinese paramilitary police guard the National Aquatics Center, also known as the Water Cube, in Beijing July 12, 2008. (UPI Photo/Stephen Shaver)

Over 100 Chinese army trucks are parked near the National Stadium, also known as the Bird's Nest, in Beijing July 12, 2008. China has identified terrorism as the biggest threat to the upcoming Beijing Olympic Games, and police are offering rewards of up to 500,000 yuan ($73,150) to people who provide tip-offs about "major security threats" during next month's Olympics, state media said. (UPI Photo/Stephen Shaver)

Rare blue skies shine on the National Stadium, also known as the Bird's Nest, in Beijing July 12, 2008. China has identified terrorism as the biggest threat to the upcoming Beijing Olympic Games, and police are offering rewards of up to 500,000 yuan ($73,150) to people who provide tip-offs about "major security threats" during next month's Olympics, state media said. (UPI Photo/Stephen Shaver)

A woman stands near the National Stadium, also known as the Bird's Nest, in Beijing July 12, 2008. (UPI Photo/Stephen Shaver)