THE last several months have brought a dramatic escalation in conflict across the Middle East, almost all of it involving tensions between Sunni and Shiite Muslims — which are in turn fueled by a power struggle between Shiite Iran and Sunni Saudi Arabia for regional supremacy.

Tehran runs a vast patronage network, backing Lebanon’s Hezbollah, Syria’s Alawite regime, Yemen’s rebellious Zaydi Houthis and Shiite militias in Iraq. Under the umbrella of Shiite solidarity, Iran provides military aid and funds industrial projects, madrasas, mosques and hospitals. And its leaders have become more vocal about their aims, with President Hassan Rouhani proclaiming himself protector of Iraq’s holy cities.

Even more aggressive is Saudi Arabia. The kingdom has sent planeloads of weapons and millions of dollars to Sunni militants in Syria, Iraq and Yemen, many of them Salafi extremists. In contrast to Tehran, Riyadh has no compunction about deploying its army openly, as in 2011, when Saudi tanks rolled into Bahrain to quell the pro-democracy rallies of the country’s Shiite majority, or during the current Saudi-led aerial campaign against Yemen’s Houthi rebels.

And yet, as new and disturbing as these developments may appear, the linkage of sectarian and secular interests is a return to the classic geopolitics of religion in the Middle East. During the 18th and 19th centuries, great powers presented themselves as protectors of specific religious groups to expand their influence and provoke unrest and division in rival states. That does not mean that the current developments are not alarming. But to fully understand them, we need to understand the nature and history of such sectarian patronage systems.

Consider Imperial Russia’s claim to be the patron of Orthodox Christendom, a claim mainly targeted at its major regional rival, the Ottoman Empire. Following the Ottoman defeat in the Russo-Turkish War of 1768 to 1774, the Treaty of Kutchuk Kainardji allowed Russia to represent Orthodox Christians in Ottoman lands. Although the treaty gave the czar only the right to build an Orthodox Church in Constantinople’s Galata quarter (which never happened), Russia used it as a basis to declare patronage over all Orthodox Ottomans. Over the following decades, it increasingly meddled in the sultan’s relations with his Orthodox subjects, undermining Ottoman sovereignty.

Similarly, Imperial France claimed to be the patron of global Catholicism, especially the Maronites of the Ottoman Levant. By the 19th century, Paris was widely recognized as having the right to intervene on behalf of the sultan’s Catholic subjects. “In the Orient, where the authority of men is measured by the number of their clients, the development of our Catholic clientele is a national interest for us,” wrote the French historian Ernest Lavisse. Paris even intervened militarily on behalf of its Catholic clients: In 1860 Napoleon III sent an expeditionary corps to the Levant to stop massacres of Maronite Christians by Druse.

The most extensive patronage efforts, however, were made by the Ottomans. From the reign of Abdul Hamid II in the 19th century, the Ottomans used their self-professed status as the defenders of global Islam to advance their influence into rival empires, from French North Africa to British India.

Interventions on behalf of religious clients frequently had bloody consequences, most notably the Crimean War, pitting Russia against the British, French and Ottomans. The conflict was triggered by Russia’s attempts to expand its control over Orthodox Christians in the Ottoman Empire and its demand for patronage over the churches and sacred places in the Holy Land, where the growing French influence over Catholics threatened Russian hegemony.

During the war, all sides tried to stir up brethren in the enemy’s hinterlands. The czar’s clerics called the Ottomans’ Orthodox population to arms, while the Ottomans tried to incite Russia’s Muslims in the Crimean peninsula and in the Caucasus. Although the responses were minimal, czarist officials accused Crimean Muslims of collaboration, causing a massive wave of refugees to Ottoman lands.

The most spectacular efforts to employ the geopolitics of religion were made by the Ottoman Empire during World War I. In 1914, the sheikh al-Islam, who oversaw the empire’s religious affairs, issued five fatwas, translated into numerous languages, urging Muslims in the British, French and Russian empires to revolt. In some cases, Ottoman agents distributed not only Pan-Islamic pamphlets but also rifles. At the same time, Russia tried to stir up the sultan’s Christian minorities. While neither side was particularly successful, the calls became excuses for targeting religious minorities across the region during and after the war.

The politics of religion undermined the Westphalian order, based on the principles of state sovereignty and territorial integrity. At the same time, these policies subverted states, fueled divisions within them — and often ended in violence.

This is also the case in the current conflict. Iran’s attempts to become the global defender of Shiite Muslims and Saudi Arabia’s efforts to lead the Sunnis have become central in their battle for mastery of the Middle East, transforming the region’s international system from an order of states to an order of faiths.

While their rivalry can be traced back to the early days of Pahlavi Persia and Saudi Arabia in the 1920s, its religious dimension came to the fore only after the Islamic Revolution of 1978-79. The collapse of states across the Middle East over the last decade unsettled the region’s sectarian status quo and led to a sustained period of escalation.

We need to take the Middle East’s new religious protectorates seriously, but we shouldn’t overrate the importance of transnational sectarian bonds. For Tehran and Riyadh, such patronage mostly serves profane interests, while Sunni and Shiite groups turn to them for help mostly because they are aware that they will be receptive. On the ground, many of Tehran’s and Riyadh’s clients have their own interests, which may diverge from those of their protectors.

The West has reacted aimlessly to this development, supporting Iran-backed Shiite militias in Iraq while endorsing the Saudi-led airstrikes in Yemen. This strategy may help establish a sort of regional status quo, but it simply manages the problem without solving it.

To weaken the order of transnational sectarian protectorates in the region, their underlying conflicts need to be resolved. The clients — Sunni or Shiite — must be sensibly accommodated in their states’ power structures, which will reduce the appeal of foreign patronage.

More important, the international community must prevent any further escalation of the struggle between their main protectors, Iran and Saudi Arabia. Solving these problems will not be easy. Religious protectorates have proven remarkably persistent; yet they have also proven too dangerous to ignore.