IN 1972 Anwar Sadat expelled Soviet military advisers from Egypt, setting the stage for decades of American dominance, and much violent disappointment, in the Middle East. In 2013 President Barack Obama surrendered America’s hegemony when he refused to take military action against Syria’s use of poison gas, and later sought a nuclear accommodation with Iran. Donald Trump, by contrast, has lobbed missiles at Syria and menaced Iran. But as he swings between threatening to crush foes and getting out entirely, the latter instinct will dominate. Sometimes events, his advisers or domestic politics may compel him to take action. But Mr Trump will mostly prove even more detached than Mr Obama.

That will make for unpredictability, ineffectiveness and prolonged chaos. Partial accords might be negotiated in Yemen, Syria and Libya, without finding lasting settlements to end the wars. Mr Trump’s “ultimate deal” of peace between Israel and the Palestinians will be stillborn, if a plan emerges at all. America’s sanctions on Iran will not dislodge its clerical regime, and will strengthen its hardliners. Jihadists will exploit any space to regroup.

In this free-for-all, the danger of new wars will be ever-present in 2019, if not by design then by mistake. The shooting-down of a Russian spy plane in September, by Syrian air-defence batteries taking aim at Israeli bombers, was a warning of how things can go wrong when so many powers are fighting different wars at close quarters. One risk is of a war pitting Israel against Iran and its allies, notably Hizbullah, the Lebanese Shia militia. Another is of Turkey being drawn into fighting against Syrian forces (and their Russian and Iranian allies) if they try to retake the rebel-held enclave of Idlib.

The politics of the Gulf will be jittery. The macabre murder in October of Jamal Khashoggi, an exiled journalist, has weakened King Salman of Saudi Arabia and his son, Muhammad, the crown prince, on whom rested the hopes of social and economic reform. That could lead to more repression, intensify palace intrigues and deepen the country’s cold war with Qatar and Turkey. Mr Trump’s sympathy for auto­cratic chums ultimately feeds instability, but he will worry more about losing influence, and defence contracts, to Russia or China

Indeed, Russia will increasingly cast itself as the indispensable power in the Middle East. By intervening in Syria in 2015, Russia saved the regime of Bashar al-Assad yet has so far avoided falling into a quagmire of the sort that exhausted America in Iraq. Russia has shown that it will stand by its allies, no matter how repulsive. It has honed its warfighting techniques, and has created a showcase for sales of military equipment.

Russia is the only country to enjoy friendly relations with all the main regional players, among them Israel, Turkey and, crucially, Iran. The key to any solution in Syria will be in the hands of Russia, not America. Even though Russia has provided air power to the region’s “Shia axis”, Saudi Arabia has co-operated with Russia to manage oil output and push up the price of crude, to the ire of Mr Trump.

Israel, Saudi Arabia and several Arab leaders have cheered Mr Trump at the risk of damaging future rel­ations with America’s Democrats. But Gulf states think he is a fickle friend, a fear heightened by Mr Trump’s warning that the Saudi king “might not be there for two weeks without us”. Russia thus provides a useful hedge against American indifference.

China is making inroads, too. It has a naval base in Djibouti and its warships have called at Gulf ports. As the biggest buyer of Gulf oil, it has a vital interest in the security of the region. But China will mostly limit itself to pursuing economic deals. It will leave the maddening political and security problems to America—or failing that, to Russia.

This article appears in “The World in 2019”, our annual edition that looks at the year ahead. See more at worldin2019.economist.com