That would be Typhoon. I'm reading it now. Funny, I'm not really enjoying it as much as the two Alec Milius books. Especially the second one (Spanish Game) was pretty good imho.
Author has some details wrong in Typhoon and that sort of thing really gets on my nerves. For example, it says stuff like "Uighurs were not allowed to speak Arabic" which is wrong because they speak their own language, which is Turkic. They write it with Arabic script, but the language isn't Arabic nor does it sound like Arabic at all.
I've fallen steadily out of love with John le Carre, who is stuck in Soviet-style intrigue (although tries to write about Al Qaeda etc). His last couple of books that I have read were astonishingly bad, I though. Especially A Most Wanted Man where nothing ever happened and details were just incorrect.