A week ago, President Donald Trump was threatening to wipe Iran off the map: “If Iran wants to fight, that will be the official end of Iran,” he tweeted. This week, the president has seemed more moderate, reportedly complaining that National Security Adviser John Bolton has pushed the administration’s policy too far toward military action against not just Iran, but North Korea and Venezuela as well.
The president’s interest in invading foreign countries—and the list of which countries he’s threatening—seems to change from moment to moment. What’s consistent, however, is a tension at the heart of the president’s approach. Both Trump and his interlocutors present their foreign policy as geared towards maintaining American primacy. And when it comes to keeping America at superpower status, risking further military conflict while neglecting the country’s diplomatic assets is exactly the wrong approach.
Despite fears about China’s rise and Russia’s resurgence, the United States remains the most powerful country in the world by a comfortable margin, spending more on its military than the next seven countries combined. The U.S. remains the only state capable of projecting power anywhere in the world. But its military is overstretched. And the current administration’s focus on maintaining an image of American supremacy risks exacerbating this self-imposed burden, hastening American decline.
From the Ottomans to the Soviets, many world powers have paid the price for overextended militaries, waging costly wars for little or no strategic gain. This isn’t a lesson the U.S. seems to have absorbed in the post-Cold War era. Particularly in the wake of the terror attacks on September 11, 2001, the United States has pursued an increasingly militarized form of global engagement, spending trillions of dollars in the so-called war on terror. After nearly eighteen years of endless war, the country seems unwilling to act realistically, to prioritize its gravest strategic threats, to reduce its military commitments and to rebalance its foreign policy.
In 1989, Yale historian Paul Kennedy argued in his classic study of global power shifts that military overstretch has often contributed to great powers’ declines: Defense costs spiral upward as countries or empires try to retain their global reach, consolidate past gains, and modernize. By the end of the sixteenth century, for example, the Ottoman Empire—which at its zenith had ruled over millions—was stretched militarily between Crimea, Central Europe, North Africa, and Persia. The Habsburg monarchy in Europe controlled a wide network of territories, from the Netherlands to Naples, from Transylvania to Spain. But its multitude of potential battle fronts led to burgeoning defense costs in the seventeenth century. Napoleon, too, ultimately stumbled on his infamous Russian invasion, falling afoul of Russia’s harsh winter while French forces were simultaneously combatting insurgents in Spain and Portugal. And in the 1970s and 1980s, the Soviet Union was stuck in foreign entanglements—including Afghanistan—while straining to keep up in a global arms race, both factoring into its demise.
As the Cold War ended, the United States was unmatched in economic and military strength. American conventional wisdom held that the dissolution of the Soviet Union marked the triumph of liberal democracy, eternally resolving the global struggle between ideologies. The U.S. was left unchallenged, unconstrained by a military or geopolitical foe. In the following decade, the U.S. championed the spread of democracy and increased its interventions into other countries and conflicts, partially in response to humanitarian concerns. It pushed Iraq out of Kuwait (in a war that, in retrospect, was refreshingly limited in its ambitions), intervened in Somalia and Haiti, backed NATO forces in Bosnia, and led the air campaign against Serbia, supporting Kosovo.