The Negotiator by Frederick Forsyth

The Negotiator is a crime novel by Frederick Forsyth, first published in 1989. The story The Negotiator includes a number of threads that are slowly woven together. The central thread concerns a kidnapping and the negotiator's attempts to solve the crime.
Late 1989: Texan oil tycoon Cyrus V. Miller reads a report he had commissioned into dwindling oil supplies in the free world and concludes that the oil fields of the Middle East must be brought under American control. Separately, a high-ranking General in the Soviet Army comes to a similarly depressing conclusion about oil access and plans a covert mission to invade Iran and take over the massive oil supplies there. Meanwhile, the President of the United States, John Cormack, meets with his Soviet counterpart Mikhail Gorbachev. With the help of a disaffected Arabist, Colonel Robert Easterhouse, Miller and his shipping tycoon counterpart Melvyn Scanlon devise a plan to inspire Islamic fundamentalists to massacre the six hundred ruling members of the Saudi royal family during jamboree celebrations; after that, American forces will go into Saudi Arabia to restore the only surviving royal - a Westernized puppet named Prince Abdullah - to power and thus secure the oil for the United States - and for Miller and Scanlon's companies. However, Easterhouse warns that Cormack won't be prepared to jeopardize the Nantucket Treaty by sending troops into the Middle East; he must be ousted from power and replaced by his vice-president, Michael Odell, who opposes the treaty... (Summary by Wikipedia)