US Senator Sam Brownback has called for a review of US policy towards Hong Kong in light of 'Beijing's recent trampling on Hong Kong's autonomy'. Senator Brownback, chairman of the Senate's Asia-Pacific subcommittee, said the US Congress passed the 1992 Hong Kong Policy Act because it trusted Beijing's promise in the Sino-British Joint Declaration of 1984 that the city would keep 'a high degree of autonomy' after the handover in 1997. But recent developments had called the city's autonomy into question, he wrote in the Asian Wall Street Journal. The senator said one important section of the act that needed to be reviewed was the 'exemption of the territory from the export controls that remain in force for the rest of China'. 'The more Beijing breaks its other promises regarding Hong Kong, the more urgent the need to guard against the risk it might do so in one further, critical arena - by diverting exports to Hong Kong of US dual-use, advanced technology into the hands of Chinese military end-users,' he wrote. The US Customs Department would have to make more on-site inspections in Hong Kong, he said. Repealing or amending the act would 'serve as a symbol that the US has given up hope of 'one country, two systems', and is focusing its attention on the national security risks that a continuation of the act in its present form might involve', the senator said. 'In the coming century, America's biggest challenge will come from a China that is economically prosperous, politically repressive and insistent on imposing its will on its neighbours,' he said. 'Hong Kong's experience with 'one country, two systems' is a harbinger that China is not mellowing or moderating with time. The memory of Tiananmen Square should remind us that China's actions in Hong Kong cannot be ignored.'