Cheung fled to China in January 1998 after failing to kidnap Chief Secretary for Administration Anson Chan, in retaliation for the jailing of his associate, Yip Kai-foon. Acting on a tip-off, the police discovered 818 kg of explosives in Sheung Shui, a part of Hong Kong, in January 1998 which they attributed to a plan by Cheung to bomb government buildings. Cheung allegedly acquired 960 kg of explosives in 1997 for $200,000 from a man in Macau, the stock was transported to Hong Kong and buried in a deserted container parking area.