China's intensifying move to assert claims over the South China Sea has given fresh impetus to a military buildup in Indonesia that will see its forces deployed with greater focus on external risks.
After years of concentrating on separatist threats across an archipelago long enough to stretch from New York to Alaska, Indonesia plans to deploy attack helicopters to its islands at the southern end of the South China Sea and expand its naval power. The front-runner for July's presidential election, Joko Widodo, aims to boost defence spending to 1.5 percent as a share of the economy, which is Southeast Asia's largest.
The strategy shift comes as China escalates disputes with the Philippines and Vietnam, fellow members of the Association of Southeast Asean Nations. China's standoff with Vietnam over an oil rig this month followed its 2012 success in taking control of the Scarborough Shoal from the Philippines.
"The focus in defence spending is moving to dealing with external threats," said Tim Huxley, executive director of the International Institute for Strategic Studies in Singapore. "There is a concern from an Indonesian perspective that the South China Sea should not become a Chinese lake and that freedom of shipping should be maintained." That is influencing Indonesia's defence spending and procurement, he said.
The military is about 40 percent of the way to developing a minimum-essential force, or MEF, by 2029, to guard its territory as it adds tanks, submarines, helicopters and jet fighters to its arsenal, Deputy Defence Minister Sjafrie Sjamsoeddin said in an interview in Jakarta. Under the MEF, the government is seeking to acquire 274 Navy ships, 10 fighter squadrons and 12 new diesel-electric submarines.
"We're part of maintaining regional stability and peace and to maintain that we must certainly have powers that support that regional strength," Mr Sjamsoeddin said.
Indonesia has sought to stay out of its neighbours' spats with China over the South China Sea, and is not an official claimant to areas in dispute. But in recent months it has said that China's interpretation of its nine dash-line map -- the basis for its territorial claims -- is seeping into Indonesia's exclusive economic zone.
Foreign Minister Marty Natalegawa said in an interview in April that he wanted an explanation of China's map and asked the United Nations to help obtain clarity.
Commodore Fahru Zaini, assistant deputy to the chief security minister for defence strategic doctrine, said in March that China's map included an "arbitrary claim" to waters off the Natuna Islands in the Indonesian province of Riau. "This dispute will have a large impact on the security of Natuna waters," he said, according to Antara News.
Indonesia has some 17,000 islands to police, stretched across 5300 kilometres from east to west. The Malacca Strait that Indonesia shares with Malaysia is a key shipping lane that links the economies of countries such as India, China and Japan.
"It's the largest country in Southeast Asia and they want to play what they think is a corresponding role," Richard Bitzinger, senior fellow at the S. Rajaratnam School of International Studies in Singapore, said. "You're not going to get that unless you develop a sizable, modern military, because at this point the military is pretty small potatoes."
Military spending increased to 81.96 trillion rupiah ($US7.1 billion) in 2013 from 72.94 trillion rupiah in 2012, according to the Stockholm International Peace Research Institute.
China's defence budget will rise 12.2 percent this year to 808.2 billion yuan ($US129 billion). President Xi Jinping has made a navy with longer reach a priority to boost China's claims in the South China Sea and East China Sea.
Despite being a maritime country, Indonesia seeks to build a "balanced force" between the army, the navy and the air force, Mr Sjamsoeddin said in the March interview, as "eventually all battles end on land." Indonesia, which is also spending on tanks, faced decades of internal discord in East Timor, an independent nation since 2002.
Indonesia isn't in an arms race and spends less than 1 percent of gross domestic product on defence, compared with 3 percent to 4 percent among other Asean nations, Mr Sjamsoeddin said. If countries in the region have heavy tanks then Indonesia should have heavy tanks, said Mr Sjamsoeddin, 61, adding some military equipment in use is older than he is.
Indonesia will deploy four Boeing Apache attack helicopters to the Natuna Islands, IHS Jane's reported on its website in March, citing General Budiman, the army's chief of staff, as a pre-emptive measure against instability in the South China Sea.
With China more assertive in the southern part of the South China Sea, "the Indonesian armed forces are strengthening their military presence on the Natuna Islands, and that includes preparing facilities on the Natuna Islands to accommodate jet fighters," said Ian Storey, senior fellow at the Institute of Southeast Asian Studies in Singapore.
"During the first decade of this century they were focused on combating internal threats, that is separatism and terrorism," Mr Storey said. "But they've been largely successful in containing those threats and I think now they're focusing more outwards, focusing on external threats."
How far Indonesia pushes back against China may depend on the presidential election, with neither candidate detailing foreign policy goals so far. Widodo, who will face off against a former general, Prabowo Subianto, pledged to boost defence spending to 1.5 percent of GDP within five years, according to his policy paper. Spending is now 0.9 percent of GDP, according to the Stockholm International Peace Research Institute .
"There seems to be a commitment to increasing defence spending, increasing Indonesia's overall military strength, more in accordance to what they see is a normal, large power in the region," Mr Bitzinger said. "They're increasingly interested too in being able to be a modern military, to project power."