Taiwan's first home-built submarine, the Hai Kun, is back at sea for testing and could be handed over to the navy next month — good news for Taiwan's defense buildup, though the boat is still a long way from being combat-ready.

• The Hai Kun went out for another dive test today, and the remaining trials are said to be the final few items on the checklist.
• The sub spent more than a month in dry dock for adjustments, partly because much of its equipment comes from foreign suppliers who often have to send in their own engineers to fine-tune it.
• Another sea test is expected this week, and if the navy and shipbuilder CSBC keep to a safety-first pace, delivery in October looks likely.
• Delivery is not the finish line: based on other countries' experience, integration tests, crew training, and commissioning take several more months to over a year before the boat is ready for real operations.

Outlook: Expect the Hai Kun to be formally handed to Taiwan's navy in October, followed by a year or more of work before it can actually patrol.