There is little doubt that years of disorder lie ahead in the Middle East as different factions try to gain control. The murder of Ambassador J. Christopher Stevens in Libya, the one American success story of the Arab Spring, is an early sign of the chaos to come; it also points to the unpredictable consequences likely to follow any Western intervention in Syria — or Iran.

As in Southeast Asia in 1975, the limits of both American firepower and diplomacy have been exposed. Financial leverage, or baksheesh, can work only up to a point with leaders struggling to control the bewilderingly diverse and ferocious energies unleashed by the Arab Spring.

Although it’s politically unpalatable to mention it during an election campaign, the case for a strategic American retreat from the Middle East and Afghanistan has rarely been more compelling. It’s especially strong as growing energy independence reduces America’s burden for policing the region, and its supposed ally, Israel, shows alarming signs of turning into a loose cannon.

All will not be lost if America scales back its politically volatile presence in the Muslim world. It could one day return, as it has with its former enemy, Vietnam, to a relationship of mutually assured dignity. (Although the recent military buildup in the Pacific — part of the Obama administration’s “pivot to Asia” — hints at fresh overestimations of American power in that region.)

Republicans calling for President Obama to “grow” a “big stick” seem to think they live in the world of Teddy Roosevelt. Liberal internationalists arguing for even deeper American engagement with the Middle East inhabit a similar time warp; and both have an exaggerated idea of America’s financial clout after the biggest economic crisis since the 1930s.

It is the world’s newly ascendant nations and awakened peoples that will increasingly shape events in the post-Western era. America’s retrenchment is inevitable. The only question is whether it will be as protracted and violent as Europe’s mid-20th century retreat from a newly assertive Asia and Africa.