Taiwan's first home-built submarine, the Hai Kun, went out for another round of sea trials — slow progress, but a sign the program is still moving forward.

• The Hai Kun left Kaohsiung port again on Tuesday morning for open-sea and dive testing.
• Taiwan designed and built the boat itself, with foreign advisers but no direct factory-to-factory technology transfer like South Korea or Australia got — making system integration much harder.
• Buying parts abroad has been blocked or slowed by outside pressure, which military analyst Chi Tung-yun calls an unusually difficult situation by international standards.
• A first submarine is a prototype by definition, so problems get found and fixed step by step, and later boats may be redesigned based on what this one teaches.
• Pushing the schedule instead of safety is the wrong trade-off; engineers are typically added near handover to hunt down software faults one by one.

Outlook: Expect continued dive tests and tuning before the navy accepts the boat, with both sides negotiating which issues must be fixed first.