Defense Secretary Robert Gates visits China (10 images)

U.S. Defense Secretary Robert Gates speaks to the press while visiting the Great Wall of China in Mutianyu, a few hours north of Beijing January 12, 2011. Gates is in China hoping to bolster uneasy military relations with Beijing, but he also voiced concern over China's latest high-tech weaponry. UPI/Stephen Shaver

Tourists hike along the Great Wall of China in Mutianyu, a few hours north of Beijing January 12, 2011. UPI/Stephen Shaver

Police do a security sweep along the Great Wall of China prior to U.S. Defense Secretary Robert Gates' visit to Mutianyu, a few hours north of Beijing January 12, 2011. Gates is in China hoping to bolster uneasy military relations with Beijing, but he also voiced concern over China's latest high-tech weaponry. UPI/Stephen Shaver

U.S. Defense Secretary Robert Gates (R) speaks to the press while visiting the Great Wall of China in Mutianyu, a few hours north of Beijing January 12, 2011. Gates is in China hoping to bolster uneasy military relations with Beijing, but he also voiced concern over China's latest high-tech weaponry. UPI/Stephen Shaver