A Chinese-born woman accused of spying on Taiwan President Lai Ching-te's family in the US will stay in jail — a sign Washington is treating Beijing's reach into Taiwanese politics as a criminal matter, not just a diplomatic one.

• Wanying Zhang, 34, was arrested by the FBI at Los Angeles airport and charged with acting as an unregistered foreign agent.
• She is accused of taking direction from Chinese officials to watch Lai's son and other family members in the US.
• A federal judge ruled she could flee and kept her locked up, rejecting a bail offer backed by property worth over a million dollars.
• She worked as a real estate agent in Irvine, California, and appeared in court in prison whites, in handcuffs and leg irons, with her husband and sisters watching.

Outlook: The case heads toward further hearings and will likely sharpen the fight between Washington and Beijing over Chinese intelligence work on US soil.