In Washington, bad ideas never die. They are simply revived by another administration that has no clue they were ever tried in the first place.

Back in 2003, Defense Secretary Donald Rumsfeld had the bright idea of asking Muslim nations to provide troops to guard holy sites in Iraq. He was oblivious to the fact that Sunni soldiers would not be welcomed by Iraq’s Shiites.

Rumsfeld returned to the idea in 2005, writing to President George W. Bush, “I believe we should seriously pursue the idea of a Muslim military contingent in Iraq,” with the goal being to “eventually provide relief for U.S. and other coalition forces.” Rumsfeld claimed that the Saudis and Qataris were supportive but, once again, nothing came of it: The Arab states had neither the capability nor the will to get involved in a costly counterinsurgency.

Fast forward to this week. The Wall Street Journal reported that the Trump administration is asking Egypt, Saudi Arabia, Qatar and the United Arab Emirates to contribute money and troops to stabilize eastern Syria so that the United States can pull its 2,000-strong contingent out. This is in line with President Trump’s comment that “we’ll be coming out of Syria, like, very soon. Let the other people take care of it now.”

Those words reflect Trump’s outlook on the entire world: For decades, he has been claiming that the United States has gotten a “bad deal” from its allies, and that it’s time for them to do more and the United States less. He has been browbeating European states, for example, to make greater “contributions” to NATO – and claiming credit for their increases in defense spending, which are actually a response to the growing Russian threat.

It would be wonderful to live in a world in which our allies take over America’s global policing role and we can focus exclusively on domestic concerns. It would also be wonderful to live in a world where you can scarf down junk food and never exercise and not wind up weighing 239 pounds — or more. But that is not the world we live in. In the real world, the United States remains, as Madeleine Albright said in 1998, the “indispensable nation.” The United States can strong-arm other nations into helping on military missions — but only as a supplement for U.S. forces, not as a substitute.

Take Syria. Is there any indication that countries such as Egypt, Saudi Arabia and the UAE are either willing or able to take over the role that U.S. troops have played in defeating the Islamic State by working with a Kurdish-Arab militia known as the Syrian Democratic Forces? Hardly. The Saudis and Emiratis are bogged down in Yemen and so bereft of effective troops that they have to rely on foreign mercenaries even to fight next door. The Egyptian military has its hands full battling a growing Islamist insurgency in the Sinai Peninsula — and trying to contain the chaos of neighboring Libya.

The Egyptians refused Saudi demands to send troops to Yemen, even though Riyadh is a major financial supporter of Abdel Fatah al-Sissi’s regime. The Egyptians have even less incentive to contribute a force in Syria, given that Sissi is drawing closer to both Vladimir Putin and Bashar al-Assad. As Oren Kessler of the Foundation for Defense of Democracies notes, Cairo is “coordinating” its policy on Syria “with the Damascus-Moscow alliance,” because it “supports the Syrian regime of Bashar al-Assad.” Sending troops to occupy eastern Syria would hardly be a pro-Assad move, because it would keep the eastern third of the country — including the country’s oil reserves — out of his hands.

The Saudis have been anti-Assad — they have supported the opposition, including, reportedly, jihadist groups — but even they are now concluding that, as Crown Prince Mohammed bin Salman said recently, “Bashar is staying.” The Saudis, presiding over an artificial state with a restive Shiite minority in the Eastern Provinces, are also wary of any attempt to redraw the current map of the Middle East. So it’s hard to imagine them sending troops, either, even if they had effective forces to contribute — which they don’t.

Sorry, Mr. President: None of these Arab allies can do what U.S. forces are doing. The American contingent is not only calling in devastating airstrikes on the enemy — whether Islamic State fighters or Russian mercenaries — but also helping the Syrian Democratic Forces to establish a functioning state. The Arabs may conceivably contribute but only if the United States remains in the lead. There is no deus ex machina: Either America keeps its own troops in Syria or it risks a revival of the Islamic State and an expansion of Iranian power. Our allies won’t do our job for us.