On Sept. 12, 2001, Americans awoke to a world that appeared forever altered. The morning before, the United States had been attacked for the first time on its own soil since Pearl Harbor. Within days, U.S. President George W. Bush would declare a “war on terror.” Analysts quickly made dramatic predictions about how the United States would change as a result, from an expanded security state to radicalization within the country to the end of irony. Some pundits turned out to be correct; others, woefully off base.

The 9/11 era is in the rearview mirror: In the last 20 years, a generation has grown up with only a collective memory of the attacks, and the United States has now withdrawn from Afghanistan. But some shifts were permanent. Foreign Policy asked seven of our columnists and contributors to weigh on how 9/11 did reshape U.S. foreign and domestic policy—and what it means for the future.

The United States is no longer indispensable.

 By Stephen Wertheim, a senior fellow in the American Statecraft Program at the Carnegie Endowment for International Peace and the author of Tomorrow, the World: The Birth of U.S. Global Supremacy.

9/11 changed how the United States understands its role in the world—but not as its leaders hoped.

After the Soviet Union collapsed, the United States opted not to retract its coercive power around the world. Instead, it embarked on a search to give this outsize power a purpose. “If we have to use force, it is because we are America; we are the indispensable nation,” then-U.S. Secretary of State Madeleine Albright said in 1998. But in the absence of a major threat and in a time of plenty, it remained unclear how much of a burden U.S. citizens were willing to bear to make their country indispensable across the globe.

At first, the 9/11 attacks appeared to solve this problem—to imbue U.S. power with an inarguable purpose. Bush immediately declared that the United States had been attacked because of the power of its example. He then responded by serving up spectacular examples of U.S. power, launching what he termed a “global war on terror” and invading Afghanistan. Even that was not enough. Iraq offered a stage to imagine that the United States, knocked back on 9/11, could transform an entire region and drive history forward. The United States had to be indispensable to the fate of the world, and what better test than on countries that could not be more distant or different from itself?