A police officer shows an unmanned aircraft during the China International Exhibition on Police Equipment 2012 in Beijing, capital of China, May 22, 2012. A total of 430 exhibitors from 13 countries and regions took part in the exhibition. (Xinhua/Liu Changlong)

　　Police firearms are on display during the China International Exhibition on Police Equipment 2012 in Beijing, capital of China, May 22, 2012. A total of 430 exhibitors from 13 countries and regions took part in the exhibition. (Xinhua/Liu Changlong)

　　Models of police special vehicles are on display during the China International Exhibition on Police Equipment 2012 in Beijing, capital of China, May 22, 2012. A total of 430 exhibitors from 13 countries and regions took part in the exhibition. (Xinhua/Liu Changlong)

　　People visit the China International Exhibition on Police Equipment 2012 in Beijing, capital of China, May 22, 2012. A total of 430 exhibitors from 13 countries and regions took part in the exhibition. (Xinhua/Liu Changlong)