Navigating the myriad complexities and cross currents of U.S.-Saudi relations since the end of World War II is a daunting process even for experienced foreign policy analysts. That journey is made easier by Bruce Riedel's masterful new book, Kings and Presidents: Saudi Arabia and the United States since FDR. Currently a senior member at the Brookings Institution, Riedel brings decades of government experience from both the policy and intelligence sides to his work. Along the way he has dealt with countless Saudi and U.S. officials with direct responsibility for the bilateral relationship.

At times, academics who attempt to write on such issues focus on high-minded theories, glossing over the importance of personal relationships in shaping major events, but Riedel's book should leave no doubt about their importance.

Kings and Presidents is chronological, beginning with a brief but instructive overview of Saudi Arabia's emergence from nomadic beginnings to regional powerhouse. From there Riedel takes the reader on a tour of relations centered on various kings and American presidents, capturing the personal dynamics between them but also the underlying issues on each side. For the Saudis this included the importance of domestic Wahhabi clerics as well as the intense desire in Riyadh for U.S. military protection. Access to Saudi oil and having global allies to confront the Soviet Union underpinned many of Washington's policy choices. Important regional actors, with Iran, Egypt, and Israel at the forefront, added to the challenges of managing the bilateral relationship. It is small wonder that the relationship has endured numerous ups and downs.

While Riedel's recounting of the historical importance of kings and presidents is admirable, perhaps the book's greatest value is a brief but persuasive assessment of the issues shaping Saudi Arabia now and in the future. Among those is persistent high unemployment, a trend that may be exacerbated, ironically, by young crown prince Mohammed bin Salman's commitment to a greatly expanded role for Saudi women in the workforce.

The crown prince, with the full backing of his father, King Salman, also is embarking on an ambitious modernization plan—Vision 2030. If successful, the plan could bring unprecedented modernization to Saudi society, the beginnings of a shift in energy policies, to the embrace of commercial nuclear power and various economic reforms. Perhaps above all, it could bring prized stability to Saudi rule as the crown prince may guide his nation for decades to come. There will be inevitable challenges and hurdles along the way. Riedel writes, "All of this has enormous implications for America … the relationship has often been strained … but its importance has never been in doubt." President Donald Trump would fully agree, having made Saudi Arabia his first official overseas destination.

The challenges are not just on the Saudi side. For the Trump administration, whose preoccupation with Iran and its desire to overturn Barack Obama's incendiary relationship with the Israelis are high regional priorities, the challenge will be to develop and maintain consistency and support for Saudi Arabia. There are few better places to plumb the depths of these issues than Riedel's work.