Washington says two US academics are being held in China, a bad sign for anyone planning academic or business travel there.

• The State Department has updated its China travel warning to flag arbitrary arrests, surveillance, and exit bans.
• Two American scholars, Youlin Chen and Min Zin, were detained after traveling to China for academic exchanges.
• Washington is demanding their release and calling hostage diplomacy unacceptable between the two countries.
• Travelers are told to assume Chinese security services can read all private emails, texts, and social media posts.
• New Chinese entry and exit rules take effect September 15, adding to the risk of getting stuck in the country.

Outlook: US-China tensions look set to worsen, and academic and business exchanges between the two countries will likely shrink further.