Two people from mainland China were arrested six days after illegally landing in Taiwan by inflatable boat, raising fresh concerns over the island’s coastal security amid its biggest annual military drill. The timing of the incident has drawn scrutiny. The two men arrived just before the 10-day Han Kuang exercise, which began on August 5, and remained at large for nearly a week before being arrested. The case only came to light on Monday after an angler reported finding an abandoned inflatable...