After Singapore gained its sovereign independence as an island-city nation, the NS (Amendment) Act was passed on 14 March 1967, under which all able-bodied male citizens of at least 18 years of age were obliged by law to serve 24 months of compulsory national service in the Singapore Armed Forces, the Singapore Police Force, or the Singapore Civil Defence Force to defend and protect the country as a sacred, honorable national duty above one's self. Upon completion of the mandatory active full-time NS, they will later also have reservist in-camp training cycles of up to 40 days annually over a 10-years period upon deployment to operationally-ready reservist units.