Indonesia is buying submarines from South Korea and coastal radar systems from China and the United States. Vietnam is getting submarines and combat jets from Russia, while Singapore -- the world’s fifth-largest weapons importer -- is adding to its sophisticated arsenal.

Wary of China and flush with economic success, Southeast Asia is ramping up spending on military hardware to protect the shipping lanes, ports and maritime boundaries that are vital to the flow of exports and energy.

Territorial disputes in the South China Sea, fuelled by the promise of rich oil and gas deposits, have prompted Vietnam, Malaysia, the Philippines and Brunei to try to offset China’s growing naval power.

Even for those away from that fray, maritime security has been a major focus for Indonesia, Thailand and Singapore.

“Economic development is pushing them to spend money on defence to protect their investments, sea lanes and exclusive economic zones,” said James Hardy, Asia Pacific editor of IHS Jane’s Defence Weekly. “The biggest trend is in coastal and maritime surveillance and patrol.”

As Southeast Asia’s economies boomed, defence spending grew 42 percent in real terms from 2002 to 2011, data from the Stockholm International Peace Research Institute (SIPRI) shows.

High on the list are warships, patrol boats, radar systems and combat planes, along with submarines and anti-ship missiles that are particularly effective in denying access to sea lanes.

“Submarines are a big thing,” said Tim Huxley, executive director for Asia at the International Institute for Strategic Studies. “They can do immense damage without being seen, without being anticipated, and they can do that anywhere in the region.”