Of the many enduring lessons of the Vietnam War, none, perhaps, is more relevant today than avoiding what Yale historian Paul Kennedy termed “imperial overstretch”—or an excessive reliance on military force to protect a far-flung and often unruly web of alliances and commitments. For many who observed or fought in that war, America’s defeat was due less to the flawed strategies of US generals than to the overextension of American power in a place of questionable strategic significance and with minimal support at home. For a time, it appeared that US policy-makers were determined to avert more Vietnam-like fiascos; but now, as in the George W. Bush era, Washington seems headed toward another foolhardy increase in military activism abroad.

March marks the fiftieth anniversary of the entry of main-force US troops into Vietnam, making this a perfect moment to reflect on the war and its long-term consequences. In this issue, former Nation editor George Black examines one of those consequences: the ongoing legacy of unexploded ordnance and Agent Orange. The Pentagon, meanwhile, is promoting its own interpretation of Vietnam, via an interactive timeline. After criticism from many scholars, who said it distorted the war’s history and character, the Pentagon backed off on some aspects of its new history. (To ensure that critical voices are heard on the subject, a group of antiwar veterans, including Tom Hayden, David Cortright and John McAuliff, are organizing a Vietnam Peace Commemoration in Washington, DC, on May 1–2.)

What is most striking in all this, however, is that many in Washington now seek to embrace the same misbegotten logic that produced the Vietnam debacle in the first place: a belief that America should confront hostile forces wherever they arise, primarily through military action.

As the Vietnam War was ending, US leaders sought to ensure that such myopia would not prevail again by adopting a series of measures—including the War Powers Resolution of 1973 and the establishment of an all-volunteer army—aimed at constraining the war-making ability of future presidents. By requiring the president to secure congressional approval for all future troop deployments, it was believed, the White House would engage in fewer ill-advised military engagements abroad; by eliminating the draft, the Pentagon presumably would be forced to pick and choose among overseas commitments, rather than embracing them all. (This was before the policy of multiple redeployments was adopted, which produced the mental and physical traumas experienced by so many US soldiers.)

For a time, these measures, along with the American public’s still-vivid recollections of the Vietnam War, resulted in a more restrained use of military force abroad (though not, of course, as restrained as many of us would have wished). The United States did not intervene in Iran to prevent the overthrow of the shah (1979), and it withdrew from Somalia following the “Blackhawk Down” incident of 1993. Limited forays were undertaken in Lebanon (1982–84) and Kosovo (1999), but without resulting in the extended deployment of US forces. On the one occasion when Washington did engage in large-scale combat, the drive to eject Iraqi occupation forces from Kuwait (Operation Desert Storm, 1991), it did so with the blessing of the international community and in accordance with limited war aims (i.e., no invasion of Iraq).

As the twentieth century drew to a close, however, conservative pundits and politicians began to chafe at what they considered excessive restraints on the utilization of US military power. These zealots, many associated with the Project for the New American Century, sought to overcome the legacy of the Vietnam War and allow for a more assertive use of force in promoting America’s foreign interests—the danger of imperial overreach be damned. At the same time, some prominent liberals also sought the relaxation of curbs on US military action in order to help protect populations at risk in ethnically divided societies.

The advocates of unbridled military action found their champion in George W. Bush, who pledged to revitalize the military and eliminate constraints on its global employment. Even before 9/11, he requested a sharp increase in military spending and proclaimed a tougher stance toward “rogue states” and other foreign adversaries. Following the 9/11 attacks, he exploited the national hysteria generated by them to fast-track his strategic agenda. In addition to surging Pentagon expenditures, he sought and obtained from Congress two measures authorizing military operations abroad. These statutes, both known as an “authorization for the use of military force” (AUMF), were said to be in consonance with the War Powers Resolution but essentially eviscerated that measure by granting the president broad powers to engage in war.

The first AUMF, adopted on September 18, 2001, gave Bush the authority “to use all necessary and appropriate force” against any persons, organizations or nations deemed responsible for the 9/11 attacks. Although many legal experts contend that this measure is aimed exclusively at Al Qaeda and other entities directly tied to 9/11, it has never been rescinded and is being used by the Obama administration to justify military operations (including drone strikes) against a wide assortment of organizations, including ISIS and the Taliban. The second AUMF, adopted on October 16, 2002, gave Bush the authority to wage war on Saddam Hussein’s Iraq. Despite the fact that US forces have largely been withdrawn from that country, this measure also remains in force.

While determined to combat remnants of Al Qaeda and other terrorist groups around the world, President Obama has tended to resist the impulse to employ force in response to overseas crises, explicitly citing the dangers of imperial overstretch. “Since World War II, some of our most costly mistakes came not from our restraint, but from our willingness to rush into military adventures without thinking through the consequences,” he declared at West Point last May. “Just because we have the best hammer,” he said, referring to US military superiority, “does not mean that every problem is a nail.”

But just as George W. Bush’s predecessors came under attack for their reluctance to employ force abroad, so Obama is being assaulted by many in Washington for being overly timid in combating ISIS, the Taliban, the Assad regime in Syria and the Russians in Ukraine. Senator John McCain, now chair of the Senate Armed Services Committee, has been among his most persistent and vociferous critics. “All of us want to find diplomatic solutions, but without sufficient leverage [read: military action], diplomacy is ineffective,” McCain declared at the Munich Security Conference on February 8. But while McCain and other Republicans are leading the charge on Obama, the president is also facing criticism from some Democrats, including presidential aspirant Hillary Clinton. Referring to Obama’s catchphrase for avoiding unnecessary military excursions abroad—“Don’t do stupid stuff”—Clinton opined, “Great nations need organizing principles, and ‘Don’t do stupid stuff’ is not an organizing principle.” [See Klare, “Don’t Do Stupid Stuff,” September 22, 2014.]

In response to all this pressure, accentuated by the media frenzy over public beheadings by ISIS, Obama is suppressing his noninterventionist instincts and moving toward a more assertive military posture. He has commenced an air war against ISIS and signaled a willingness to extend the US military mission in Afghanistan. The administration is also stepping up military aid to pro-Western rebels in Syria and considering the delivery of battlefield weapons to the Ukrainian military. Obama’s newly chosen secretary of defense, Ashton Carter, is vigorously campaigning to overcome Congressional restraints (known as sequestration) on higher military spending.

To cap all this off, Obama has asked Congress to approve a new authorization to use military force, or the new AUMF. This one is aimed at ISIS, and would give the president the power to use military force as “necessary and appropriate” to degrade and defeat that entity. Unlike the first two AUMFs, however, it sets certain limits on military action: a time limit of three years, and an injunction against US troop engagement in “enduring offensive ground operations.” The final text, however, is up to Congress, which may eliminate or soften the restrictions proposed by Obama.

In the coming weeks, Congress, the media and the Washington punditry will argue the merits and flaws of Obama’s AUMF. Many (though not all) Republicans seek to eliminate the constraints included in Obama’s version, while many (though not all) Democrats aim to impose even tougher limitations. Progressives will be caught in a tough dilemma: whether to support a watered-down version or oppose the measure altogether.

There are reasons to support Obama’s AUMF as submitted by the White House: it merely codifies what is already happening in Iraq and Syria while imposing limits on further escalation, and the Obama draft also rescinds AUMF-II, the original authorization for military action in Iraq. But approval of this measure, like that of the first two AUMFs, would also provide legitimacy to a process of expanded presidential warmaking and set the stage for follow-up measures granting the White House even greater authority to conduct military operations abroad. It would mean, as Obama would have it, choosing a hammer to solve a complex, multifaceted problem. And if Vietnam teaches us anything, it is that overreliance on the military to address such problems inevitably leads to costly, protracted and inconclusive military entanglements abroad.