Taiwan is warning that a new Chinese border-control law taking effect Sept. 15 makes travel to China riskier for a long list of Taiwanese people, and the risk is personal safety, not just paperwork.

• Taiwanese politicians, civil servants, retired soldiers, judges, teachers, opinion leaders and "Bluebird" protest participants are seen as likely targets for questioning at the border.
• The rules let Chinese customs demand a reason for leaving the country and even inspect data on travelers' phones.
• Beijing can bar its own citizens from leaving for three years if they did something abroad deemed harmful to national security, or if they broke export-control rules.
• Anyone who has worked for an international NGO or a human rights group is also advised to stay away, since Beijing already holds a lot of personal data on Taiwanese people.
• The tightening is tied to Xi Jinping keeping his grip on power and China's push to overtake the United States, with more checks by more agencies than before.

Outlook: Expect tougher screening at Chinese borders from Sept. 15 and more Taiwanese travel warnings as cases of questioning or detention surface.