China to deliver 2,500-ton submarine to one of US' key allies in Asia

Thailand, a longstanding U.S. ally in Asia, has signed a deal to purchase a Chinese-built Type 039A (S26T) diesel-electric submarine, marking a significant development in regional defense dynamics. The deal, finalized in September 2025 after years of delays due to Germany’s refusal to supply engines amid the EU arms embargo on China, now involves a Chinese-made engine following successful reliability tests. The 2,550-ton submarine, featuring advanced Stirling-type air-independent propulsion alongside a conventional diesel engine, is expected to be delivered by 2028. The contract includes technology transfer and training provisions, extending construction by about 40 months. Originally planned for multiple units, budget cuts have limited the purchase to one submarine. This acquisition signals Thailand’s intent to assert strategic autonomy and maintain a balanced foreign policy, rather than a shift away from its alliance with the U.S. Analysts interpret the purchase as a message to Washington that Thailand seeks flexibility and independence in its defense posture, especially after past