Taiwan's government is telling its citizens that going to China just got more dangerous, especially for business people and chip workers.

• China's new exit-and-entry rules take effect September 15, giving legal cover to questioning and detaining travelers.
• Border officers can demand travelers hand over and unlock phones, tablets, and laptops on the spot.
• One clause lets officials block people from leaving if they are suspected of harming national industry or technology security.
• Taiwanese business owners, managers, and workers in chips and clean energy are seen as the most exposed — able to get in but possibly not out.
• Enforcement is pushed down to the county level, where local officials may over-enforce rather than risk missing someone.

Outlook: Expect confusion and heavy-handed enforcement in the first weeks, and more Taiwanese companies rethinking whether staff need to travel to China at all.