Singapore will announce in the next few months plans to replace its ageing F-16 fighter jets, its defense minister said, listing a number of manufacturers that could be in the running for a deal potentially worth billions of dollars.

Singapore’s fleet of around 60 F-16 jets are at the tail end of their service and Ng Eng Hen told reporters it needs to make a decision to replace them soon because training pilots and building facilities for new models can take up to 10 years.

With Southeast Asia’s largest defence budget, the wealthy city-state is a key prize for global arms companies as it looks to invest in new technology and upgrade its equipment.

“Whether it’s Typhoons, whether it’s F-35s, whether it’s Sukhois, even now Chinese-made stealth fighters. I mean these are the usual suspects that you have to look at,” Ng said.

He was referring to the Eurofighter Typhoon that is built by Britain’s BAE systems and F-35s from U.S.-based Lockheed Martin. Sukhoi is a Russian manufacturer.

A modern fighter jet costs roughly about $20-$100 million depending on the manufacturer.

Singapore should make a decision in the next few months “to make sure that we can replace our F-16s in time,” Ng added.

Singapore’s F-16s first entered service in 1998. The country has typically used U.S.-made aircraft in the past, making the F35s - a variant of which appeared at the city-state’s airshow back in February - a likely successor.

The head of Lockheed’s international business said in February that Singapore was “seriously evaluating” a future purchase of F-35 jets - one of the world’s most advanced fighters which start at around $80 million (60.56 million pounds) each.

He said initial talks with Singapore were centred on the F-35B short take-off and landing variant, which he described as “a nice fit for a smaller land-constrained environment”.

Media reports show that Singapore had intended to buy four F-35s by around 2022, with the option to purchase another eight, but held off taking a decision on this in 2016.

Other F-35 customers in Asia include Australia, Japan and South Korea.

Britain’s BAE has offered Singapore’s neighbor Malaysia a U.K. government-backed financing deal to replace the country’s combat jets with their Eurofighter Typhoon.