There is a “general sense of strategic uncertainty in the region” given China’s rise and doubts about the U.S. ability to sustain a military presence in Asia, said Ian Storey, a senior fellow at the Institute of Southeast Asian Studies.

“Southeast Asian countries will never be able to match China’s defence modernisation,” he said, citing Vietnam’s push for a deterrent. “If the Chinese did attack the Vietnamese, at least the Vietnamese could inflict some serious damage.”

SIPRI says Indonesia, Vietnam, Cambodia and Thailand took the lead in boosting their defence budgets by between 66 and 82 percent from 2002 to 2011.

But the region’s biggest spender with the best-equipped military is Singapore, a tiny island that is home to the world’s second-busiest container port, a global financial centre and a major hub for oil, gas and petrochemicals.

The wealthy city-state, along with Malaysia and Indonesia, sits on the Strait of Malacca that links the Pacific and Indian oceans. A teeming shipping route, the strait is also a narrow “choke point” with huge strategic implications for the energy, raw materials and finished goods flowing east and west.

At $9.66 billion, Singapore’s 2011 defence budget dwarfed Thailand’s $5.52 billion, Indonesia’s $5.42 billion, Malaysia’s $4.54 billion and Vietnam’s $2.66 billion, IISS says.

The situation is far less intense than in North Asia where China, Japan, the United States, Russia and the two Koreas are involved. But Southeast Asia seems to be following the trend of pursuing military systems that can be used offensively.

“It’s an indefinite process,” said Huxley at IISS. “Governments are likely to go on devoting resources - that are increasing in real terms - to defence and military modernisation.”

Official data on the amount and purpose of the spending is often opaque - how much goes to boots, bullets and salaries and how much to advanced hardware that can project power?