The great task of diplomacy in the 21st century is a sad and dreary one, namely managing the decline of Muslim civilization. There is a parallel to the great diplomatic problem of the late 19th and early 20th century, the dissolution of the Ottoman Empire, which the diplomats bungled horribly.

It is no job for the idealistic, namely the Americans, nor for the squeamish, namely the Europeans. The breakdown of civil order in a great arc from Beirut to Basra has already displaced 20 million people and raised the world refugee count from 40 million in 2011 to 60 million in 2014, with scores of millions at risk. After it failed to build democracy in Iraq and Afghanistan, the United States fell into a sullen torpor in which serious discussion of intervention in the regime is excluded. The hypocritical Europeans averted their eyes until millions of desperate people appeared on their doorstep, and remain clueless in the face of the worst humanitarian crisis since the last world war.

That leaves Vladimir Putin as the last, best hope of a region already halfway over the brink into the abyss. That is a disturbing thought, because the Russian leader has played the spoiler rather than the statesman in his wrangling with Western powers over the past decade and a half. Nonetheless, Russia has an existential interest in sorting out the Levant. Muslims comprise a seventh of the population of the Russian Federation, and the growing influence of ISIS threatens to give a fresh wind to terrorism inside Russia. Mr. Putin might rise to the occasion.

Putin might for example offer a compromise solution that I first heard suggested by Erik Prince, the counterterrorism expert and entrepreneur: force Syrian president Basher Assad out of power, but let Moscow pick his successor. At that point Turkey and Saudi Arabia could claim victory and withdraw their support from Sunni extremists (or be compelled to do so by the United States), and Iran could be compelled to withdraw its Revolutionary Guards from the theater and cut off support for Hezbollah. The efforts of the international community then could turn to destroying ISIS. There would be no glorious era of Arab democracy, no Arab spring, no happy ending, just a less murderous sort of despotism and an armistice rather than a real peace between Shia and Sunni. That is as good as ever it will get in that miserable region.

Unlike the feckless Europeans, who can’t abide a single casualty, or the disgusted Americans, Putin has the nerve to put boots on the ground in Syria. Large-scale combat operations by foreign armies will not solve the region’s problems, but the willingness to take bullets is the ante in this particular poker game. Putin is the only foreign leader who has paid it.

I do not know what Putin will do. But it seems clear that Russia has a deep interest in fostering such an outcome. It is at no risk of a Muslim majority by mid-century, contrary to some of the shock estimates circulating at the fringe of academia. In an April 2015 study, the authoritative Pew Research Center estimates the total fertility rate of Russian Muslims at slightly below Russia’s overall fertility rate: “While Muslim fertility is well above replacement level in many countries, it is below replacement level in Iran (1.6) and in much of Eastern Europe, including Romania (1.5) and Russia (1.6).”  Projections of a Muslim majority in Russia by 2050 failed to consider the collapse of Muslim fertility rates.

But that does not mitigate Russia’s concern about ISIS. Chechens are the largest contingent of foreigners fighting for ISIS in the Levant, including a celebrated Georgian Army special forces commander, Tarkhan Batirashvili who has been fighting in Syria since 2012. Jihadist groups in the Russian Caucasus, meanwhile, began to offer their loyalty to ISIS’ putative caliphate earlier this year. Both as a training ground for Muslim terrorists and a galvanizing force for Russian jihadists, ISIS represents a threat to Russia.

Russia tilted towards Iran in the region in order to pressure Sunni jihadists, as Putin has told Western diplomats in just those words. I have heard the same explanation from Chinese analysts for Beijing’s rapprochement with Tehran: Like Russia, China has virtually no Shia Muslims, but has a great deal to fear from Sunni fundamentalists. Russia and China were playing a balance-of-power game not much different than Washington’s, although with none of the sentimental illusions harbored by the Obama administration.

For Russia as well as China, the notion that Iran would provide a counterweight to Sunni jihadists in the region was a gigantic blunder. The Muslim world is in the throes of civilization collapse, and it is ridiculous to treat its juridical entities like pieces on a chessboard. The P5+1 nuclear deal with Iran legitimized Iran as a regional power and gave it an immediate dividend of $150 billion. This provoked the Sunni powers to throw more resources behind jihadists who are bleeding Hezbollah to death in Syria, and taking a severe toll on the Iran Revolutionary Guard Corps in Syria as well as Iraq.

The presence of 20 million people of military age, most of them without prospects, provides a virtually limitless supply of cannon fodder. Like Europe’s Thirty Years’ War, the mushrooming of mass armies that support themselves by living off the land leads to uncontrollable, self-sustaining conflicts.