Saudi King Salman in January (Reuters)

Nawaf Obaid is a visiting fellow and associate instructor at Harvard University’s Belfer Center for Science and International Affairs.

Just two months after the passing of King Abdullah, Saudi Arabia’s extensive intervention in Yemen on Thursday should serve notice to the world that a major generational shift underway in the kingdom is sure to have far-reaching geopolitical ramifications.

The new Saudi leadership — centered on a cadre of youthful, dynamic royals and technocrats — is developing a foreign policy doctrine to address long-standing regional tensions. This doctrine is based on the legitimacy of the Saudi monarchy and the centrality of the kingdom to the Muslim world. As the custodian of the holy mosques of Mecca and Medina, Saudi Arabia is uniquely positioned to rise above the fray of the past decade and begin bridging the considerable gaps dividing the main Sunni nations. With almost 90 percent of Muslims identifying as Sunni, and the Saudis at the epicenter of the Sunni world, the Saudis believe they can meet an urgent need for a united Sunni front against Shiite Iran, as well as the terrorist movements tearing the Arab world apart.

Abdullah’s successor, King Salman, has inherited a disastrous situation in the region. With the Obama administration abandoning the United States’ historical responsibilities and, by extension, most of its prestige in the Middle East, the Saudis have no choice but to lead more forcefully, more coherently and, above all, more sustainably. This mantle is based on the kingdom’s conservative religious base and its unique Arab tribal inheritance. More tangibly, it is backed by $150 billion in spending to upgrade the Saudi military to allow it to engage enemies on two major fronts simultaneously, eliminating the need to rely on foreign assistance in defending the homeland.

The Saudis’ new doctrine harks back to the foreign policy of the kingdom in the 1970s and 1980s. Then, the Saudis worked tirelessly to end 15 years of bloody civil war in Lebanon by securing the 1989 Taif Agreement, which established special relations between Lebanon and Syria and set up a political system that guaranteed power-sharing among religious denominations. Expect the Saudis to push for similarly far-reaching and inclusive pacts as solutions to the chaos now engulfing Syria and the other hot spots around the region.

The Saudi leadership faces a number of issues, but most of them stem from Iranian aggressiveness. In Yemen, the Iranian-backed Houthi coup that brought down the central government has taken pressure off al-Qaeda in the Arabian Peninsula and produced anarchy, with full-blown civil war appearing more likely every day. In Syria, the Assad regime’s efforts to hold on to power, supported again by Iran, have brutalized the population and breathed life into the terrorist Islamic State. In Iraq, successive central governments supported by Iranian-controlled Shiite militias have destroyed any semblance of statehood and created the conditions that permitted the Islamic State to seize vast swaths of territory. In Lebanon, the Iranian-created Hezbollah movement reigns supreme in a country that is barely holding together. And Tehran-supported Hamas holds Gaza in its grip while a resolution to the conflict between the Israelis and Palestinians remains far in the distance.

The Saudis and their main Sunni allies know that only a unified bloc of like-minded states can keep Iran in check. In pursuit of this, the Saudis already have started reaching out to most of the major Sunni states — chief among them Turkey, Egypt and Pakistan — to begin the complex process of reconciliation.

Finally, there are the Iranian nuclear negotiations, which the Saudis are watching closely. Saudi Arabia simply cannot allow Iran under any scenario to use its “near status” as a nuclear power to expand its influence and prestige around the region. Settling for a so-called U.S. “nuclear umbrella” is unfathomable to Riyadh. Whatever deal the Iranians get, the Saudis will pursue an equivalent program to reach nuclear parity.

While this list of problems appears daunting, a new era is dawning in the Middle East. For all the tough rhetoric coming from its leaders, Iran is under severe pressure from U.N. sanctions and the collapse of oil prices, which could have dangerous consequences for the stability of the Iranian state. The Saudi doctrine is premised on reinforcing these geo-economic realities while pushing Iran’s weakened ability to project power abroad to the point of breaking.