Vice Admiral Talengsak Sirisawad, Naval Operations Department chief, today said the submarines were needed to protect Thai marine interests worth Bt24 trillion.
He added that the submarines would reinforce Thailand's bargaining power when negotiating with other countries to defend national interests.
Talengsak said the Navy considered the purchase carefully and found it was beneficial for the economy and for national security.
The Navy spoke up to defend the deal following a public outcry when government coalition MPs voted to purchase two more submarines as the economy sinks under the impact of Covid-19.
The subcommittee for procurement, ICT, state enterprises and revolving funds, which is vetting the budget bill for 2021, voted 5:4 on Friday to spend Bt22.5 billion on two more subs from China.
The vote was deadlocked after four coalition MPs from the Palang Pracharath, Democrat and Bhumjaithai parties approved the Navy budget for the China-made subs, while four opposition MPs voted against. The opposition lawmakers were from Move Forward, Pheu Thai and Seri Ruam Thai (Thai Liberal Party).
The chairman of the subcommittee, a member of the pro-military Palang Pracharath Party, then voted in support, resulting in approval of the Navy budget.
The planned purchase is part of a deal signed by the military-backed government of Prayut Chan-o-cha to buy three subs from China. The first submarine was purchased in 2017 and will be delivered in 2024.
Vice Admiral Tirakul Kanchana, the Navy’s Comptroller-General, said the purchase of all three submarines will cost Bt36 billion. For the first sub, Thailand is paying over Bt13 billion in instalments between 2017 and 2023.
Tirakul said the purchase of two additional subs is part of this same deal, not a new procurement. The Bt22.5 billion payment will be divided into seven annual instalments of Bt2 billion-Bt3 billion, using the Navy regular annual budget, not an extra budget, he said.
Navy Chief of Staff Adm Sittiporn Maskasem said any delay in purchasing the subs could affect the country's marine security and Thailand’s credibility in international trade.