Joshua Teitelbaum, senior research associate at the Begin-Sadat Center for Strategic Studies (BESA), and professor of Middle East studies at Bar-Ilan University, briefed the Middle East Forum on a conference call on Feb. 4, 2016. Saudi Arabia's recent

Joshua Teitelbaum, senior research associate at the Begin-Sadat Center for Strategic Studies (BESA), and professor of Middle East studies at Bar-Ilan University, briefed the Middle East Forum on a conference call on Feb. 4, 2016.

Saudi Arabia's recent execution of the prominent Shiite cleric Nimr al-Nimr sparked a sharp crisis between the desert kingdom and its Iranian neighbor that can be best understood in the context of the historic Sunni-Shiite rivalry.

Saudi Shiites constitute a small, beleaguered minority (10-15 percent of the total population) in a theocratic Sunni kingdom that derives its legitimacy from a Wahhabi doctrine that considers Shiites polytheists and heretics, leading to long-standing discrimination and oppression. The position of Shiites substantially worsened following the creation of the Islamic Republic of Iran in 1979 and its aggressive pursuit of worldwide Shiite leadership, ebbing still further during the 2011-12 upheavals due to their support of the struggle of their Shiite brethren in neighboring Bahrain for political and socioeconomic reforms.

Responding with iron-fist repressive measures, the Saudi authorities played the sectarian card by launching a press campaign and delivering anti-Shiite mosque speeches to stoke Sunni opposition. For his part, Nimr catapulted himself to the forefront of the demonstrations, openly calling for Shiite martyrdom and the toppling of the Saudi royal family. A video clip of his inevitable arrest went viral, dangerously fomenting already inflamed Sunni-Shiite passions.

Last year's change of Saudi leadership to King Salman Abdul Aziz, aided by his young and energetic son, Minister of Defense and Deputy Crown Prince Muhammad bin Salman, resulted in a muscular and assertive foreign and defense policy. Feeling betrayed by the Iran nuclear deal and Washington's attendant empowerment of Tehran as the regional power broker, the Saudis see President Obama as essentially pro-Shiite.

A cartoon from the Saudi daily Okaz depicts Saudi Arabia as restraining Iran from igniting fires across the region.

Geopolitics abhors a vacuum so, given the American retrenchment, Iran's resurgent hegemonic ambitions, Iraq's post-Saddam transformation into a de facto Shiite state, and the threat of Tehran's Houthi protégé in Yemen, the execution of Sheikh Nimr sought to send a clear message to Iran and its Shiite proxies of Riyadh's determination to not tolerate dissent and to protect itself against whatever forms of Shiite aggression lie ahead.

The vector of Saudi policy arches towards a more assertive regional posture in Yemen, Syria, Iraq, and towards Iran. Increased cooperation with China, and maybe even Russia — even though it now supports the Assad regime — is in the cards. These possible security partners may play a role in Saudi plans to expand its armed forces to create the possibility for Riyadh's regional projection of force — not unlike the capabilities possessed by Israel.

But this may still be dependent on a greater question: what will be the direction of American foreign policy? Is the Obama policy of American retrenchment a sea change, a lasting legacy that will guide future US leaders? Or will the next president return US policy to one of actively protecting allies instead of creating a balance of forces? The answer to that question must await the first Tuesday in November.

Summary account by Marilyn Stern, Middle East Forum Board of Governors