April 28, 2007: Singapore, which received four refurbished Swedish coastal submarines in the last decade, is about to receive two more modern, and much more capable, boats. The four older Challenger class subs each displace 1,100 tons on the surface, have a crew of 28 and are armed with four 533mm and two 400mm torpedo tubes. Sixteen torpedoes are carried, as well as several dozen mines externally.

The four A-11 Challenger Class (ex-Sjöbjörnen Class), were purchased in 1995. These are old boats, first was launched in 1968. The Challenger Class were modified for tropical conditions (air conditioning and better corrosion resistance), and also received weapons system and sensor upgrades. The Challengers have done very well in training exercises against American and Australian warships.

Two years ago, Singapore bought two Swedish A-17 Vastergotland submarines, which are expected to enter service within two years. These more modern boats will replace two of the current Challenger-class submarines. These boats were built in the late 1980s for Sweden, but were taken out of service in 2004 as a result of downsizing. For Singaporean service, the two Vastergotlands have received air conditioning and the Stirling Air Independent Propulsion (AIP) System. The AIP uses diesel fuel and Liquid Oxygen in a closed system, and enables the sub to stay underwater for weeks at a time.

The new combat and sensor systems in the two Vastergotlands are rumored to include a lot of American technology. Singapore is one of Americas best allies in the region, and Singapore has received modern military technology from the U.S. before. The Singapore Vastergotlands are a little larger than the Challengers, to accommodate the AIP system. With the AIP and the state-of-the-art sensors, these boats will be the most capable submarines in the region. Since Singapore sits astride the Straits of Malacca, the busiest shipping channel in the world, that is no small thing. The new subs will be capable of hunting down and destroying any of the subs or surface warships owned by nations in the region. But just two of these subs is not an offensive force, but a deadly defensive one. That sends a message.