Now Saudi foreign and security policy has gone into overdrive. Rather than carefully pushing back Iran and enrolling broad support for this effort, the approach has been haphazard, unsettling and counterproductive — and Iran remains one step ahead.

Saudi Arabia’s intervention in Yemen, on behalf of the government forces fighting against Iranian-backed Houthi rebels has been costly and inconclusive, even after more than two and a half years. In fact, it could lead to the very outcome that Riyadh most wanted to prevent: the transformation of the Houthi movement into something akin to Lebanon’s Hezbollah — except much closer to Saudi borders. Indeed, unless the war in Yemen comes to an end soon, those well-armed, Iran-backed militants will soon sit atop a shattered state and a starved society.

The Saudi-led blockade of Qatar has been more successful. The effort to tame that country’s assertive regional policies has worked and the crisis has now been put on the back burner of international diplomacy. That said, the reputational cost has been high for all: A dispute framed by the Saudis as a struggle for the future of the Middle East is seen in many capitals as an unnecessary and disruptive clash of wealthy royals.

The latest Saudi venture — the forced resignation as prime minister of Lebanon and probable house arrest of Saad Hariri, once a favorite ally of Riyadh — has bewildered many in Lebanon and elsewhere. It is also likely to backfire. This move plays into the hands of Iran and Hezbollah, who duplicitously pose as rule abiding, despite having undermined the Lebanese state for decades, assassinating rivals, plunging the country into foreign wars and exporting fighters across the region. In contrast, Saudi Arabia was backing state institutions and working through established politicians like Mr. Hariri. What Riyadh has now in mind — and in store — for Lebanon is unclear.

In fact, if its goal is to counter Iran, Riyadh is picking the wrong battlefields.

Lebanon and Yemen are peripheral countries, where wars are costly and complex, outcomes ambiguous and returns low. In the Middle East, the balance of power is determined in Syria and Iraq. But in those countries, the costs are high and the risks even higher. And in both places, Iran is well ahead.