The Bourne Supremacy. Robert Ludlum

The Bourne Supremacy. Robert Ludlum - Robert Ludlum David Webb, AKA Jason Bourne, is drawn into events in China and Hong Kong. Another assassin is being used to take out rival groups prior to the handover, and using his name.
The US trick Bourne into going after him, but it rapidly spirals out of their control.

There's a lot of tense moments as the government plays with Webb's/Bourne's mind to make him their assassin by putting at risk the things he cherishes.

There are several plot threads running through the book, and the characters are well written in each one.