The sub plan, which has surfaced periodically over the years, re-emerged when Gen Prawit on Wednesday said the country needed to equip its navy with submarines as part of efforts to modernise the armed forces.
The defence minister said chances were good that the navy can fulfil its deep yearning for submarines, but he stopped short of saying when funds would be allocated.
"I can't say exactly how many percent (chance there is). But when I said the navy has a chance, it means more than 50% or 60%,'' he told reporters. The budget could be around 36 billion baht.
In July, the navy opened an ultra-modern, 540-million-baht submarine base and training centre in Chon Buri province, even though the country doesn't own a single sub.
Thailand has not had a submarine since 1951, but has been trying for several years to get some. In 2011, the military negotiated to buy six small used submarines from Germany for 7.7 billion baht and considered buying two larger new vessels from South Korea, but both deals fell through.
Navy officials say they want submarines to protect the Gulf of Thailand and Thai interests on the high seas. But one worry is the spat over the South China Sea's Spratly Islands — claimed in part or in part or in whole by Brunei, China, Malaysia, Philippines, Taiwan and Vietnam — could erupt into a regional conflict that destabilises the region.
The high-ticket price was the factor, however, that ultimately sank the submarine plan. This week, however, Gen Prawit asserted that the country needs submarines to keep up with other Asean countries Malaysia, Singapore and Vietnam all have them.
Keeping up with the neighbours
A navy source said the navy quietly set up a committee commanded by chief of staff Thanarat Ubon to dust off the project in December after Gen Prawit gave navy officers a green light. The panellists visited Germany, Spain and South Korea, with China set to be their next stop in investigating sub sellers.
The navy wants to buy two diesel-powered submarines with displacement of 2,400-3,000 tonnes. The source said the Chinese-made Yuan class is favoured by the committee due to its specifications. The U-class from South Korea and Germany also pinged the sonar screen.
Chinese Defence Minister Chang Wanquan offered to sell weapons with special conditions and ''friendship price tags'' to Thailand twice when Gen Prawit visited Beijing in November. The offer, which also included 10-year payment plans, was repeated when the Chinese minister came to Bangkok last month.
The source said navy chief Adm Kraisorn Chansuwanit planned to swap the position between Adm Thanarat and Narongphol Na Bangchang, who is a deputy chief of staff at the Supreme Command, in a mid-year reshuffle to speed up the sub project. Adm Narongphol was a key figure on the submarine team before he was moved to the Supreme Command, the source added.
The Type 039A submarine (NATO reporting name Yuan-class) is a class of diesel-electric submarine in China's People's Liberation Army Navy.