The Straits Times looks at 20 years of securing Singapore following the Sept 11 attacks. Sept 11, 2001: A series of coordinated attacks through hijacked planes by Al-Qaeda against the United States takes place, resulting in the deadliest terrorist attack in history. Dec 9, 2001: Six Singaporean Jemaah Islamiah( JI) members are arrested by the Internal Security Department, with 15 more detained within a month, for being involved in plans to attack Yishun MRT station and several foreign embassies