The SAR 21 is a bullpup assault rifle designed and manufactured in Singapore, chambered for the 5.56x45mm cartridge. First revealed and subsequently adopted by the Singapore Armed Forces (SAF) as its standard service weapon in 1999, it was designed and developed over a four-year period to replace the locally license-built M16S1 by the Ministry of Defence (MINDEF), Singapore Army and the former Chartered Industries of Singapore (CIS), presently ST Engineering Land Systems.