, Singapore – In minutes, one of Singapore's busiest highways can be transformed into a runway for screaming air force fighter jets, its narrow meridian strip of potted bougainvillaea bulldozed to the side.

That road from the main airport is just one example of the meticulous defences that abound in this tiny island state, where decades of peace and prosperity have done little to dispel a deeply-rooted sense of military vulnerability.

Now Singapore is about to spend more than $1-billion on 20 warplanes to replace its ageing A-4SU Super Skyhawk combat jets in its biggest-ever fighter jet investment.

The decision could have ramifications for the region, spurring other Asian states into upgrading their own fighter fleets, some of which date back to the 1970s, experts say.

“Singapore is one of the first countries in the region to acquire new aircraft,” said Manuel Magalhaes, European aerospace and defence programme manager at consultants Frost & Sullivan. “This is almost like a psychological game. As soon as a country starts buying new aircraft, others will follow.”

Asia is a key market for US and European aerospace firms, making up almost 50 percent of their total profits, he said.

Candidates to replace Singapore's US-made Skyhawks include Boeing's F-15E Strike Eagle, along with its F/A-18E/F Super Hornet, Lockheed Martin's F-16 Fighting Falcon, Russia's Sukhoi Su-30MK, the Typhoon from European consortium Eurofighter and France's Dassault Aviation's Rafale.

All of those multi-mission aircraft are much larger and more effective than the old Skyhawks, which are considered good light bombers but are not fighters at all.

Neighbouring Malaysia decided in August on a $900-million purchase of 18 Sukhoi Su-30MKs, very big jets much more powerful than those of its regional neighbours. Singapore's Ministry of Defence may announce its short-list of three firms this month, local media reports say.

Some experts see Lockheed Martin's F-16 as a likely choice as Singapore already has F-16s in its air force and might not want an entirely new line.

In February this year, Singapore, a staunch US ally, joined the US-led F-35 Joint Strike Fighter (JSF) programme, sparking rumours that the Americans might land the deal.

“Singapore's fighter requirements are notable for their transparency and professionalism,” said Richard Aboulafia, vice-president at Teal Group, a Washington-based aerospace and defence consulting firm.

“The only complication is that they are aware of the importance of good strategic relations with the US and the benefits of US equipment acquisition,” he said.

“The F-16 has the best chance…,” he added.

Each year Singapore spends about S$8,25-billion (R35-billion), five percent of its gross domestic product, on defence to fortify an island half the size of Los Angeles.

The Singapore Straits Times newspaper reported that the new fighter planes would cost around R490-million each and that maintenance was estimated at around R2,1-billion for each plane over 20 years.

Given the cost, Singapore's Ministry of Defence is taking its time in coming to a decision. It began looking for a replacement fleet in 1998, and the process of evaluating the current selection has already been delayed by six months.

Magalhaes reckons Boeing stands a good chance. “Politically, Singapore is closer to the US than it is to Russia or Germany,” he said. “Most likely, it's going to be Boeing.”

Singapore and Washington – allies during the Iraq war – signed a free-trade agreement this year.

European Aeronautic Defence & Space Co of Germany and France is a part owner of Eurofighter, but another partner, Britain's BAE Systems, is handling the Typhoon sales push in Singapore. Finmeccanica is the third partner in Eurofighter.

But some analysts say Singapore's participation in the US-led F-35 Joint Strike Fighter programme could lead to the purchase of European jets.

“To placate European concerns that Singapore was tying itself too firmly to US aerospace, Singapore could consider a token European fighter buy,” said Aboulafia at Teal.

A report in the French La Tribune newspaper in June said Dassault Aviation was “virtually guaranteed” of being short-listed by Singapore for the upcoming fighter contract.