Southeast Asian navies have expanded apace over the past 20 years. This expansion has largely been centred on the commissioning of new frigates and fast attack craft. Now, though, regional navies are increasingly focused on the acquisition of diesel electric-powered attack submarines.
The main drivers of these programmes are:
Indonesia's underwater combat capability, which for many years relied upon two small, partially active, 1980s vintage German-built submarines, is surging ahead. April 2019 saw the launch, at PAL's Semarang Dock facility, of Alugoro, Indonesia's first indigenously constructed submarine, a Type 209/1400 boat designed by South Korea's DSME. It will join the already-commissioned, DSME-built, Nagapasa and Ardadedali. Three more of the class are on order from DSME.
The Type 209/1400 submarines displace 1,400 tonnes, and are capable of 21 knots. They will be armed with both torpedoes, and Harpoon anti-shipping cruise missiles.
The Royal Malaysian Navy (RMN) operates two French-built Scorpene-class submarines, both commissioned in 2009. These teardrop-hulled, 20-knot boats are optimised for operations in Southeast Asia's warm and saline waters. Six torpedo tubes can launch Blackshark 553mm wire guided torpedoes, and SM39 Exocet anti-shipping cruise missiles.
The Scorpenes are based at Seppanggar in Sabah. Another RMN submarine base is being constructed at Langkawi to facilitate easier access to the Indian Ocean
Kuala Lumpur announced in 2018 that it intended to acquire two more submarines.
Myanmar's previously insignificant navy has made huge advances over the past decade, and few analysts were surprised when Yangon confirmed in 2017 that it wanted to acquire submarines, particularly as naval rival Bangladesh has commissioned two former PLA Navy Ming-class submarines.
New Delhi, seeking to forestall possible Chinese involvement in Myanmar's submarine programme, is reportedly shortly to supply Sindhuvir, a Russian-built Indian Navy Kilo-class boat, to Myanmar for use as a training submarine.
President Rodrigo Duterte confirmed in August 2019 that two submarines will be ordered for the Philippine Navy, a service which has never previously operated such craft.
Recent reports indicate that France has offered to supply a pair of Scorpene subs, while Russia is promoting its Kilo class.
The technologically advanced, highly competent, Republic of Singapore Navy (RSN) has operated submarines since 1995, when the first of four refurbished ex-Royal Swedish Navy Sjoormen-class boats entered service as Challenger-class submarines.
2011-2013 saw two more second hand Swedish subs, this time of the more modern Vastergotland class, enter RSN service, and the subsequent retirement of two of the Challenger class.
The Vastergotland-class boats, Archer and Swordsman were extensively upgraded by Kockums in Sweden for RSN service, with the fitting of Kockums V4 -275 Sterling air independent propulsion (AIP), and new sonar, targeting and climate control systems.
Now on order from TKMS of Germany are four Type 218SG submarines. These 70-metre, 2,200-tonne, boats will feature AIP, advanced sensors, and eight torpedo tubes. The first of these boats, Invincible, was launched in February 2019.
RSN submarines are reportedly very actively engaged in electronic intelligence gathering.
The Royal Thai Navy (RTN) was an early regional operator of submarines, but its flotilla of Japanese-built subs was decommissioned, without replacement, in the 1950s. The RTN, though is now returning to the submarine scene.
The RTN established a submarine crew training facility in 2014, and Bangkok subsequently announced that CSIC of China had been contracted for the supply of the first of a projected three S26T submarines.
The S26T is an advanced version of the PLA Navy's Yuan submarine, and will reportedly feature AIP.
In parallel with this project, the RTN is pursuing the construction of a class of midget submarines, reportedly to displace 150-300 tonnes, and to be named the Chalawan class. BMT of the UK have been contracted to oversee the project.
Prior to 2014, the Vietnam People's Navy (VPN) operated no submarines. Now, though, the VPN has a flotilla of six Russian-built Kilo Project 636 submarines based at Cam Ranh Bay. The vessels were constructed at the Admiralty Shipyard, St. Petersburg.
These reportedly very quiet submarines have a submerged displacement of 4,000 tonnes. Maximum speed is 24 knots, range is 7,500 nautical miles.
Armament of the VPN Kilos consists of 533mm torpedoes, fired from six tubes, as well as 3M14E Klub-S land attack missiles.
According to some reports, VPN Kilo subs are regularly deployed to monitor the movements in the South China Sea of Hainan Island-based PLA Navy nuclear powered submarines.