Military build-up in Southeast Asia has been a noticeable trend, as shown by force modernization, although there is not necessarily political will to improve military effectiveness. The phenomenon has been attributed to various factors, including protecting economic interest, self-reliance in the reduction of US commitment in the region, domestic and foreign tensions, and the need to replace colonial era material, but also some non-military related factors such as national prestige, political corruption, etc.

Almost all Southeast Asian nations modernized their militaries since 1975, the ending year of the Vietnam War, and continued since then, even though the process was slowed after the 1997 Asian financial crisis. During this period, military personnel, tanks, armored personnel carriers (APCs), medium-range howitzers, missile-armed naval vessels, combat helicopters and combat aircraft increased and modernized. However, experts pointed out that this still did not fit the definition of an arms race.

Southeast Asia had seen an increase in absolute defense spending, the biggest increase compared to other regions of the world, even though they are relatively unchanged in proportion to the country's GDP. The South China Sea dispute was cited by some analysts as the motive, but others pointed to steady military expenditure per capita and relatively small in change of military inventory compared to old equipment replaced.

Statistics Flag Active military Reserve military Paramilitary Total Per 1,000 capita(total) Per 1,000 capita(active)

Countries colspan=2 0 0 0 0 0 0 4 0 0 0 0 0 0 200 0 0 0 0 0 0 0 0 5 14 0 0 378 0 5 0 0 11 18 0 5 97 45 0 0 25 0 0 0 0 0 0 0 0 0 12 0 0 48 0 0 0 0 2 4 0 2 67 32 0 0 185 0 0 0 0 4 2 0 2 155 27 TC 0 0 0 2 0 0 4 1 0 0 22 27 0 0 163 0 4 0 0 6 6 0 6 126 25 0 9 288 1 5 0 0 10 7 0 0 143 47 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1800 0 0 0 0 4 6 0 6 97 47 0 0

Regional overview Noticeable modernization trends in Southeast Asia are acquiring of technological sophistication, such as guided munitions, and investment in command, control, communications and computer processing, as well as intelligence, surveillance, reconnaissance systems (C4ISR). Multi-role fighter aircraft, maritime reconnaissance aircraft, modern missiles (including anti-ship missiles, beyond visual range air-to-air missiles, air-to-ground missiles, tactical ground-to-ground missiles), modern artillery systems, submarines and warships equipped with the new electronics and anti-ship missiles, including Scud missiles, late-model MiG 29, F16, F18 and Su-27 jet fighters, MRLS systems, and modern frigates armed with Harpoon and Exocet missiles became more widespread. However, no regional nation seems able to adopt Revolution in military affairs (RMA) due to lack of military resource, technology and armed force specialists. Almost every military increased its conventional capabilities, while archipelago nations adopted rapid deployment. Navies tend to cover their lack of mine counter-measures, maritime surveillance, offshore patrol and anti-submarine capabilities. Another notable trend is the acquisition of advanced fighter aircraft, with Singapore being the first to introduce fourth-generation jet fighters.

Southeast Asia was the fastest-growing military spending region in the world between 2009 and 2018. Between 2009 and 2018, total regional spending was increased by 33 percent from $30.8 billion to $41.0 billion (constant 2017 US dollars). The region's share of global arms import increased from 5.8 percent in 1999–2007 to 8.1 percent in the period 1999–2018. China's rising to a regional military power and aggression in the South China Sea was cited as the motive for this period, and countries that are parties to the conflict saw the largest increase. Even though the proportion of military spending to each country's GDP remained constant and still did not fit the definition of arms race, the action-reaction pattern and low trust among the nations with lack of regional dispute resolution mechanisms meaning that there could be a risk of misunderstanding in the future.

In official defense policy documents often cited terrorist, armed rebels, pirates, smugglers and organized crime, including humanitarian assistance and disaster relief as the reasons of arms acquisition. However, the acquisition of tanker aircraft, combat aircraft, anti-submarine warfare aircraft, air-to-ground missiles, air defense systems, coastal defense systems, submarines, and surface combat ships, as well as amphibious assault landing ships, were the evidence that the nations perceived foreign threats. The equipment can engage with foreign threat far from home country, and could be seen by neighbors as "aggressive".

There is also a number of factors, even unreasonable, to arms acquisition, as in the countries with strong military influence in politics. Myanmar's military spending has been decreased after 2015 political reform, but the opposite is true for Thailand after the 2014 coup.

+ Military spending of Southeast Asian nations, 2009–18 Country %Change Numbers of years increased vs. decreased SEA 7, 3 2, 8 10, 0 7, 3 N/A 4, 1 (incomplete data) 4, 6 N/A 3, 3 (incomplete data) 6, 4 6, 4 8, 2 3, 7 8, 2

By country

Brunei The country has its share of military spending relative to its GDP higher than most SEA nations, but fluctuation of oil price means that it had to scale down its spending. Most of its imports were ships and naval weapons.

Cambodia Between 2009 and 2018, Cambodia increased its military spending every year. Amount to $525.1 million in 2018, the spending accounted for an average of 2.1 percent in 2015–18. A border issue with Thailand in 2008 and 2011 is the motive. Moreover, increased political influence of the military since 2017 may likely also played a role. The country's military inventory did not change much during the period, only to replace decommissioned weapons. By 2018, the country had shifted more to land weapons, although it is subjected to change in the future.

Indonesia Indonesia saw the necessity to modernize its armed forces from Communist takeover of Vietnam in 1975 and the poor performance in its invasion of East Timor in 1976. After the declaration of EEZ in the 1980s, the modernization process has concentrated on improving maritime security by developing its naval, air force, and rapid deployment capabilities, considering its geographical features as a large archipelago, sea lanes and waterways. Even though it would not to want to lag behind Singapore, but it appeared relaxed for its proportion of defense spending. The average annual spending in the 1990s was about 1.5% of its GDP, the lowest compared to its neighbors, showing its priority on economic development and declining status of the military in the post-Suharto era. The emphasis on modern modernization efforts was on its marine corps and navy, with construction of a major naval base in Teluk Rate.

The country increased its spending sharply in 2009–13, accounting to 109 percent increase. However, since then the share of military spending to the country's GDP was decreased in order to balance its budget. Its priority is to replace older systems, mostly acquiring new combat aircraft and warships, and one goal of its defense policy is to expand domestic arms production with deals include licensed production and some level of technological transfer. Its long-term plans include up to 230 new combat aircraft, several dozen frigates and up to 12 submarines by 2030, even though it seems not possible given the current spending rate.

In 2016, the country is the strongest military in SEA, its inventory include some of the most modern weapons from the West and Russia, including Russian Sukhoi-27/30 jets, American F-16s, German Type 209 submarines, Leopard II RI main battle tanks, and Ukrainian BTR-4M amphibious armored personnel carriers.

Laos The military spending data of Laos was kept secret, but the amount is the second lowest in the region. The number is likely to increase when, threatened by Cambodia, it ordered new aircraft and tanks in 2017 and 2018.

Malaysia The Malaysian Armed Force was experienced in counter-insurgency and jungle warfare from the multi-decade long communist insurgency. Recognizing its vulnerabilities from its long coastlines and offshore oil and gas fields as well as regional situations, the country began military build-up program PERISTA in 1979. Analysts commented on its will to catch up with its neighbor on conventional capabilities. Apart from being halted in 1997 economic crisis and its aftermath, the modernization was continuous and show determination of develop all-round capabilities and counter Singaporean build-up. The result would be an armed force with enhanced maritime security and power projection capabilities.

Malaysia allocated military budget according to its economy which fluctuated in the recent years. It remained focus on naval buildups, and it published a long-term plan for improving air force capabilities.

Myanmar The military of Myanmar was neglected until 1988 coup. The military junta then underwent a modernization program aimed at covering its obsolete weapons and increase the manpower. However, the program had been a quantitative expansion. Even though it managed to subdue various ethnic insurgencies, its military is still considered weak compared to its neighbors. Its priority was given to buying of cheap weapon systems. But its investment on local arms industry resulted in ability to produce light weapons, light armored vehicles, land mines, mortars and ammunition. It increasingly focused outwardly to Thailand's growing military capabilities and China's influence over the country.

Myanmar's spending data was incomplete as the case of Laos'. Its spending is likely to have decreased after civilian government since 2015, and Western countries enforced arms embargo is gradually lifted in practice. Its main security problems are still ongoing internal conflict, but recent maritime conflict with Bangladesh drive naval spending. It also expressed interest in developing its own arms industry and technological transfer.

Philippines The Philippines was preoccupied with internal insurgencies and factionalism, coupled with a military alliance with the US and continued presence of naval and air bases meant that there was no pressure of military modernization. After the decreased US aid and conflict in the Spratly Islands, Military Modernization Bill was signed into law in 1995, but the actual program was launched in 1999, partly due to the economic crisis.

Its military spending increased by 50.3 percent between 2009 and 2018 in real terms, however, its economic burden remained stable. The increase was in part due to higher salary of servicemen. The Armed Forces of the Philippines priority shifted to territorial defense. However, due to criticism of Duterte's policies, some Western countries refused to export weapons to the country. It then shifted attention to make deals with Russia, China and Israel. Its inventory is one of the most outdated in the region, and the Revised AFP Modernization Act of 2013 outlined its effort to modernize its armed force by 2027. Eighty-seven percent of arms imports were aircraft or ships.

Singapore Singapore has developed its military continuously, not being halted by 1997 crisis. Its leadership considered the armed forces necessary to act as a deterrent, given the country's status as a city-state in a volatile region. It embraced the idea of RMA and enhanced its military technologies. Singapore was the most powerful military in Southeast Asia as of 2004, and there is a continuous political will and funds to do modernize its military. Apart from importing new vehicles into its army, navy and air force, its army also introduced locally built infantry fighting vehicles.