What is the main conflict in The Bourne Supremacy by Robert Ludlum?

A spectacular assassination of a high-ranking Chinese official in Hong Kong suggests that the legendary hired killer, Jason Bourne, has come out of retirement. Officials from the U.S. CIA and State Department, who created the original myth years ago, know better, and know that if the assassin continues his work, Asia will be plunged into economic chaos and perhaps warfare. If that happens, all nations including the U.S. will have to take sides, and World War III could result. Fearing David Webb, a professor of Oriental studies in a small university in Maine, will not again accept the role of Bourne, codenamed "Delta" and "Cain" in earlier black operations, the government instead kidnaps his wife, Marie, to force the point.