The 1957 Cadasan coup d'etat (Cadasan: Kudeta Cadasa 1957) happened in Cadasa on March 17, 1957. The Labour president Tan Yeng Sen was feared by the US and Western Bloc due to his socialist policies. A group of right-wing high-ranking Cadasan Armed Forces military officers led by general S. P. Situmorang and the Chiu twins then seized power in a coup. Not a single drop of blood was shed and at noon, Situmorang declared martial law over the radio and suspended the constitution.