Isolationism is back. The White House figures that few voters care about Trump’s betrayal of the Kurds or foreign policy in general. Trump beams that he is fulfilling his promise to get us out of endless Mideast wars. Democratic “debaters” scarcely mention foreign policy. Sen. Elizabeth Warren argued that “we ought to get out of the Middle East,” echoing Trump, not the best guide.

True, most of the time, most Americans prefer isolation. Only massive jolts persuade them to intervene overseas. Foreign policy is inherently an elite occupation, something Trump uses against the establishment. The trouble is, isolationist bouts are invariably followed by periods of strong interventionism. Applying one to an absurd high point generates the opposite, reinforced by rancor.

Isolationist waves sweep the country after every war. After Independence, the Alien and Sedition Acts blocked American involvement in the French Revolution and its attendant wars. But we exported much grain to the Continent, which Britain tried to stop. Result: the War of 1812, in which the British occupied eastern Maine. To prevent British return, we built Fort Knox on the Penobscot.

The Monroe Doctrine told Europeans to keep out of our hemisphere and we’ll keep out of theirs. After the Civil War, in which the British almost recognized the Confederacy and the French briefly occupied Mexico, we turned inward until the war with Spain and Philippines insurrection, which many opposed.

Americans turned isolationist after World War I, leading to the original America First committee. Most ignored the Axis danger until Pearl Harbor, after which we blanketed the globe with Cold War interventions until Vietnam, our first endless war. After Nixon withdrew from Vietnam, we pulled back into “risk aversion” and intervened little (Grenada, Panama) until the 1991 Gulf War. Jolted by 9/11, we vowed to make the Middle East democratic, neglecting its complete lack of democratic foundations. Result: chaos.

Such repeated alternation demonstrates how overinvolvement leads to isolationism, then reverses. The underlying, insoluble problem is that we can neither totally control the outside world nor totally withdraw from it. A middle ground of moderate, prudent involvement would be desirable, but such middle grounds veer to one side or the other, fueling frustration and rage. I too wish we could stay out of the Middle East, but negative consequences are likely:

Syria’s Kurds, facing ethnic cleansing, fight the invading Turks. Kurds have battled occupiers since Alexander the Great and the crusaders. Promised their own country after World War I, Kurds were divided among Turkey, Iran, Iraq and Syria. In fighting Turkey and Iraq, Kurds got help from the Soviet Union, Iran and the U.S. but were betrayed. The latest demoralizes our armed forces. U.S. military and civilian officers retire early and criticize policy.

Turkey, once our geostrategic ally, has turned bitterly anti-American and could leave NATO for Russia, a historic reversal. Ater a long, bloody civil war against Kurdish breakaway terrorism, Turkey claims Syria’s Kurds are also enemies. Erdogan phoned this to Trump, who instantly agreed but then sent Erdogan an insulting letter. A few U.S. troops might have kept northern Syria stable.

Iran is emboldened; its “Shia corridor” through Iraq, Syria and Lebanon is secure, putting Iran and its Hezbollah client near Israel in the Golan. Fighting easily ignites, and Hezbollah would rain Iran-supplied rockets on Israel, which will retaliate massively. If, say, a thousand rockets a day hit Israel, how long before it would go nuclear?

Saudi Arabia joins Israel in fighting Iran, letting Israeli jets refuel on their way to bomb Iran. Iranian drones and cruise missiles take out Saudi oil installations (which they’ve already done). Mines and raiders make the Persian Gulf too dangerous for oil exports, which produces global recession.

Saudi Arabia destabilizes. Almost five years of Saudi airstrikes in Yemen against Iran-supported Houthis fail to win but inflict massive civilian casualties. Sending a 15-man hit squad to dismember Jamal Khashoggi flashes regime insecurity. Trump and the Saudi crown prince shrug off his murder. We’re supposed to defend Saudi, but sarcastic bone-saw jokes undermine enthusiasm. A Saudi-Iran war could overthrow the House of Saud, which demands U.S. protection. With declining U.S. military presence to counter Russia, Trump effectively hands the region to Putin, who triumphantly just met Saudi, Emirati and Turkish leaders.

ISIS regroups and terrorizes again, targeting Americans. The president stands accused of failing to “protect and defend,” an impeachable offense. America’s devalued power and reliability really isolate us. Cowardice and betrayal end American-led world order.

Keeping out of the Middle East is tempting but not as simple as Trump portrays — “Let them play in the sand.” The above scenarios feed off each other and are already under way. No one likes endless wars, but a total pullout could force us to re-engage at costs far higher than at present. Senator Warren (and Rep. Tulsi Gabbard) should avoid Trump’s policies.