Taiwan's government is telling citizens with human rights or political backgrounds to think hard before flying to China — a warning aimed at anyone who has worked for an NGO or in politics.

• A Taiwanese man was held and questioned for six hours on arrival in Shanghai over past part-time work for Amnesty International.
• Questions covered his duties, contacts with politicians and activists, and any work touching China, Hong Kong, the Uyghurs or Tibet; he was let go only after agreeing to turn around and fly home.
• His family believes Chinese security services keep lists of people tied to international rights groups, and that he was flagged at the border without knowing it.
• Taiwan's Mainland Affairs Council says even people who left politics or activism years ago have later drawn long prison sentences in China.

Outlook: China brings in new entry and exit rules on Sept. 15 that Taipei expects to make crossings riskier still, so more travel warnings are likely.