Deputy Prime Minister Prawit Wongsuwon insists the navy will go ahead with its plan to buy a second Chinese-made submarine amid reports of a possible delay.
His assurance was echoed by Adm Ruechai Ruddit, the navy commander.
However, Adm Ruechai said he is ready to adjust the plan to match the current situation.
Gen Prawit on Monday appeared doubtful when he was asked by media crews to comment on a report indicating the navy will suspend the submarine plan and instead buy less expensive frigates.
"Where does that rumour come from?" Gen Prawit asked.
"There's no change to the plan. Everything remains the same."
The cabinet, under the previous coup-appointed government, gave the green light to the navy's plan to buy three submarines from China worth 36 billion baht altogether.
The scheme was put before the cabinet on Oct 25, 2016, and required a budget over 11 years.
"We are still following our plan," Adm Ruechai said, referring to the submarine purchase in the 2020 fiscal year.
A source said the navy is waiting for parliament to approve the 3.2-trillion baht fiscal 2020 budget before pushing ahead with the second 12-billion-baht submarine purchase.
While insisting the navy needs more submarines to reinforce its maritime operations, Adm Ruechai admitted the purchase will be determined by many factors, especially money.
"We have to consider whether we have enough money," he said.
"Everything can be flexible. We can't simply buy it purely out of will. We have to assess the situation."
Two years ago, the cabinet approved the first purchase of a Yuan Class S26T submarine worth 13.5 billion baht from China which is set to be delivered next year.
The navy had struggled for years to buy submarines, following over 60 years of no new purchases.
Its earlier plan to buy six German-made second-hand submarines at a price of 7.7 billion baht was rejected in 2011 during the then Yingluck Shinawatra government amid doubts over cost-effectiveness and transparency.