In 1979, Leslie Gelb and Richard Betts released a book on U.S. involvement in Vietnam, entitled “The Irony of Vietnam: The System Worked.” Unlike most previous treatments of the conflict, Gelb and Betts didn’t argue that the U.S. failure in Vietnam was the result of a poor foreign policymaking process. Nor did they argue that policymakers had been misinformed or misled about the conflict. They didn’t even argue that policymakers were under any illusions about how unlikely success in Vietnam was.

Instead, Gelb and Betts argued that – while the war in Vietnam itself was an abject failure for American foreign policy – the U.S. decision-making system actually functioned as it was meant to throughout the period of increasing U.S. involvement in the war. As they describe:

“With hindsight, it seems evident that the costs of the strategy of preventing defeat were incalculable. But at the time of the crucial decisions, the costs of accepting defeat appeared to be incalculable. The system in this case coped as democracies usually do: by compromising between extreme choices, satisfying the partisans of neither extreme of opinion within the government but preventing the total alienation of either.”

As the authors show, the central question about American involvement in Vietnam wasn’t why U.S. involvement in Vietnam happened, or why policymakers chose to deepen it over time, but rather why U.S. policymakers considered it vital that Vietnam not be lost to communism in the first place.

At each key decision point, policymakers chose to do the minimum possible to avoid a communist victory. Their basic argument is simple: the U.S. decision-making system was uniquely suited to fiddle with tactical choices while enabling policymakers to avoid hard strategic questions.

Stop me if this sounds familiar.

Donald Trump’s speech on Monday night carried strong echoes of Gelb and Betts’ work, as he recommitted the United States to an open-ended, ill-defined military mission in Afghanistan.

Much has been made of Trump’s flip-flop on Afghanistan policy, shifting from his campaign rhetoric – which promised that the United States would be getting out of the nation-building business – to a policy scarcely different than that pursued by his two predecessors. But it makes sense in the context of Gelb and Betts’ Vietnam argument.

Trump advisors – the ‘generals’ he is so proud of – were able to convince him that all the other Afghanistan options were worse. Even though a continued U.S. commitment in Afghanistan is unlikely to produce success, he agreed to an approach which largely hopes to prevent losses.

Just as policymakers did in Vietnam, Trump is fiddling with tactics without asking the broader strategic questions. To be precise: Is it actually a key U.S. interest today to stabilize Afghanistan and prevent further Taliban gains?

Certainly, it would be better for everyone if Afghanistan were stable, prosperous and democratic. But it is substantially harder to argue that it is a core U.S. interest. The key arguments in support of this proposition – laid out once again in Monday night’s speech – are questionable. 

Indeed, the idea that an Afghanistan without U.S. military presence will result in future terror attacks is so misleading that scholars have described it as the ‘safe haven myth.’ Terror groups operating out of ‘safe havens’ have been responsible for only 1% of the terrorist attacks on the United States; 9/11 is an extreme outlier.

Others focus on past U.S. commitments, arguing that we’ve spent too many lives and too much effort to withdraw now. Yet as behavioral economists would note, this is a sunk-cost fallacy, biasing policymakers to continue existing commitments lest the previous efforts be ‘lost.’

Rather than question how to avoid losing in Afghanistan, policymakers should compare the potential costs of losing to the costs of continuing our commitment.

Unfortunately, while Gelb and Betts’ arguments can help us understand how even good policymaking institutions can result in poor foreign policy outcomes, they offer no real solution for how to short-circuit this process.

In the case of Vietnam, popular discontent with the war ultimately made it so costly for policymakers that they were forced to reconsider their options. In the case of Afghanistan, where an all-volunteer force has replaced a popular draft, the 16-year war is largely invisible to public opinion.

As a result, America’s forever war looks set to continue for a long time.