Operation Yellowbird, or Operation Siskin (simplified Chinese: 黄雀行动; traditional Chinese: 黃雀行動), was a Hong Kong-based operation to help the Chinese dissidents who participated in the Tiananmen Square protests of 1989 to escape arrest by the Chinese government by facilitating their departure overseas via Hong Kong. Western intelligence agencies such as Britain's Secret Intelligence Service (SIS a.k.a. MI6) and the U.S. Central Intelligence Agency (CIA) were involved in the operations. Other contributors included politicians, celebrities, business people and triad members from Hong Kong—forming the "unlikely" alliance which sustained the operation for most of its duration.