According to foreign media citing the Singapore Ministry of Defense, in late November, the Singapore Navy held a retirement ceremony for the last two Challenger class submarines at Changi Naval Base. According to reports, with all these second-hand submarines retired, the Singapore Submarine Force will become an underwater force primarily composed of brand new submarines. The Singapore Challenger class submarine originated from the Swedish Sea Serpent class conventional submarine and was later renamed the Challenger class. It is mainly used for crew training, underwater warfare exploration, and other purposes. Subsequently, Singapore purchased more high-performance Sagittarius class submarines from Sweden. In order to promote the upgrading of submarines, Singapore signed a contract with German company ThyssenKrupp Marine Systems in 2013 to purchase four Changsheng class conventional submarines. In September of this year, Singapore held an official commissioning ceremony for the first two submarines, while the remaining two are currently undergoing testing and are expected to enter service soon. Singapore is accelerating the upgrading of its submarines, which will significantly enhance its underwater combat and maritime defense capabilities, and indirectly reflect the rising trend of submarine procurement in Southeast Asian countries. (New Society)