There are so many trouble spots in the world, it is comforting to know — or at least to believe — that Saudi Arabia isn't one of them.
Until the United States surpassed the kingdom a few months ago, Saudi Arabia was the world's biggest producer of oil, a country of enormous wealth and the beneficiary of perhaps the largest wealth transfer in history.
It appears a stable monolith. It was untouched by the revolutionary movements of so-called "Arab Spring," while nations such as Syria, Egypt and Libya saw their governments toppled, their economies ravaged and, in the worst case, the eruption of bloody civil war.
However, Saudi stability is a myth. As I wrote in "The Sunni Vanguard," Saudi Arabia is neither monolithic nor stable. If we look ahead three to five years, its regime may well be destabilized by domestic or foreign forces.
The reasons for Saudi instability are not what you might expect. Though the age disparity between the rulers and the ruled is greater than in almost any other nation, the death of King Abdullah (now almost 90) is not likely to set off a war of succession because his probable successors would not govern differently from him.
Abdullah has been spending lavishly on social programs to keep the populace quiet. This may be a seed of long-term instability because that spending has created a generation of younger Saudis who are accustomed to being unproductive. Moreover, the worst-kept secret in Washington is that — as a famously leaked State Department cable says — they have been lavishly subsidizing Sunni terrorist groups for many years.
Within the next three to five years, Saudi Arabia faces serious threats from abroad. The authors of these problems are the United States, Iran and the Saudis themselves.
The Saudis have spoken harshly of President Obama's foreign policy as it affects Syria and Saudi Arabia. The Saudis correctly view the Syrian civil war as Iran's attempt to plant a Shiite proxy on their border. They have done everything short of sending troops to Syria to oppose the regime of Bashar Assad in the civil war. They have publicly divorced themselves from President Obama's now-failed diplomatic initiative designed to remove Mr. Assad's chemical weapons and have made it very clear that they will go their own way, leaving America powerless in the region.
The Saudis rightly fear that the Syrian civil war will likely result in a new version of Mr. Assad's regime, under the thumb of Iran and Russia, with the power to project insurgent attacks penetrating Iraq and then across the Saudi border. What they fear most, however, is that it may be within Iran's power to create a revolt within Saudi Arabia.
Iran has every reason to do so in retaliation for Saudi Arabia's opposition to Iran's attempt to turn Syria into a satellite state, with the help of the Assad government and Russia.
When Shiite forces threatened Bahrain in 2011, Saudi troops helped the Sunni government restore order. Bahrain is on the eastern border of Saudi Arabia. The popular majority in the eastern Saudi provinces, where much of the kingdom's oil reserves and export facilities sit, is Shiite. As such, they have no loyalty to the Saudi regime and could be the lever for Iran to instigate a revolt against the Saudi government.
Last but not least in evaluating Saudi instability is the certain advent of Iran's nuclear arms.
With the nuclear deal Mr. Obama has made with Iran, he has set Saudi Arabia adrift in search of its own nuclear weapons. When Saudi Arabia unravels, it will signal — with one exception — the end of America's ability to affect events in the Middle East.
The exception will be our ability to help Israel defend itself.
Jed Babbin is a former deputy undersecretary of defense in the George H.W. Bush administration and co-author of "The Sunni Vanguard" (London Center for Public Policy, 2014).