In September 1963, after much discussion and negotiation with Prime Minister Tunku Abdul Rahman of Malaysia, Singapore merged with the Federation of Malaya (including North Borneo and Sarawak) to become the state of Malaysia.  Lee Kuan Yew believed that this merger would not only ensure the survival of the island financially, but that the union would also help combat ... the breakaway left-leaning Barisan Sosialis political party in Singapore. Opposition Barisan Sosialis party members including Lim Chin Siong, Lim Hock Siew, and other activists had already been dealt a heavy blow with arrests and lengthy detainments in February 1963 during the government’s supposed anti-communist roundup known as Operation Coldstore.