Trying to understand the forces at work in The Sympathizer, and thinking about Conrad

With surprisingly little affect, the narrator of Viet Tranh Nguyen's The Sympathizer pulls off the assassination of a fellow exile whom they suspect of being a spy - working in league w/ the newly established VC government in Viet Namh, even though he knows the he himself, the narrator, is the spy and the victim was an innocent dullard. All this raises, or perhaps begs, the question: why is all this so important? Why are these Vietnam exiles still either (a) working in secret for the new Communist government (i.e., the narrator, the eponymous Sympathizer - why can't he go back now that the movement he'd been secretly supporting is in power? Won't they recognize and accept him? Or is he more valuable as a plant in the U.S.?) or (b) plotting to overthrow the newly installed government. It seems that there is literally nothing they can do to change the course of history in their homeland, and of course the vast majority of Vietnam exiles quietly and effectively joined the American mainstream/ So I don't have a real grounding in what's going on - how the right-wing exiles are plotting (we don't see them do much but drink and sulk), why the VC should fear them, it's all a mystery. Some wonderful writing in various sections, but I keep wishing this novel were more Conradian (viz. The Secret Agent or Under Western Eyes) with real intrigue and high stakes.