• But the two Democratic candidates are also unique in what they've said about how the US should behave as a global power. A historian of US foreign policy explained how Sanders and Warren would use this power.
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The 2020 presidential campaign, like the ones before it, has focused on domestic issues.

Vermont Sen. Bernie Sanders and Massachusetts Sen. Elizabeth Warren , both tireless proponents of workers and vociferous critics of the financial elite, have been leading voices on issues like healthcare and economic policy as the Democratic primary unfolds.

Read more : 43 years ago, a US Cold War ally assassinated one of its biggest critics with a car bomb in the heart of Washington, DC

Presidential candidates' foreign-policy visions receive less attention, despite the president having outsize power to shape US foreign policy. Just as Sanders and Warren have distinguished themselves on domestic matters, they stand apart from their rivals when it comes to defining the role the US should have in the world.

In an email interview, Daniel Bessner , a professor at the University of Washington's Henry M. Jackson School of International Studies who specializes in the history of US foreign policy, explained how Sanders and Warren conceive of US power and what they could do if they get the chance to wield it.

Christopher Woody: How do Sanders and Warren view the US's role in the world, and how do they differ from Democratic and Republican establishment views?

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Daniel Bessner : The first thing to appreciate about Sanders and Warren is that, when it comes to specific policies the two candidates have articulated, there isn't much daylight between them.

Both have come out against so-called "endless war"; both have affirmed they want to restrict the power of the imperial presidency; and both have emphasized the importance of centering the concerns of labor, as opposed to capital, when determining American policies of international trade.

At the same time, however, both have embraced radically different understandings of what the US role in the world should be. To put a fine point on it, Sanders is an internationalist and Warren is a nationalist; that is to say, Sanders, unlike Warren, does not center the American citizen in his vision of foreign policy. Instead, Sanders adopts a more capacious understanding of US foreign policy that takes the interests of all the world's peoples particularly, all the world's workers into account.

One sees this in the language the two deploy. Where Warren's campaign makes clear that she will "stand up for the American economy, fight to protect American workers, and defend American values," Sanders' campaign strikes a more international tone, declaring that should Sanders win, "he will change the terms of the global economy to lift up workers everywhere, reversing the race to the bottom."

Warren's views are relatively close to the fundamental assumptions of the bipartisan foreign policy establishment. In essence, she believes that some bad actors have gotten the United States in some bad wars, while other bad actors have helped capital at the expense of labor, but all told the world requires US "leadership."

Sanders, who knows the tragic history of US foreign policy during the Cold War quite well, is more skeptical of this position and seems more willing to cede some of the United States' hegemonic power.

Woody: What are Sanders' and Warren's attitudes toward foreign intervention specifically? Have they elaborated on under what circumstances they'd see it as appropriate?

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Bessner : Both Sanders and Warren have expressed skepticism over military intervention, particularly military intervention in the Middle East and Central Asia, two regions in which the United States has been bogged down in fruitless wars for decades.

In general, Sanders has articulated a more categorical rejection of military intervention; for instance, in a statement on Venezuela, he asserted that "the United States has a long history of inappropriately intervening in Latin American countries; we must not go down that road again."

As far as I'm aware, Warren has not yet released any similarly categorical statements against military intervention, though she has cosponsored a resolution that would prohibit the unauthorized use of military force in Venezuela.

All told, I believe both candidates are post-Iraq War candidates in that they are quite skeptical of military intervention, but my sense is that Sanders, who has long been associated with US anti-imperialist movements, would be more willing than Warren to risk political capital and take on the U.S. military to prevent the use of force abroad.

Woody: Both Sanders and Warren have spoken about empowering regular people and challenging entrenched political and economic interests; how does that influence their respective approaches to foreign policy?

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Bessner : When compared with Warren, Sanders has been far more willing to promote a foreign policy that centers ordinary people as opposed to governments.

He has been quite clear that his foreign policy vision is, in a sense, post-nationalist; as he has argued , only "a strong global progressive movement that speaks to the needs of working people, that recognizes that many of the problems we are faced with are the product of a failed status quo," can challenge the kleptocratic and autocratic capitalism that has emerged in the United States and elsewhere.

Warren might very well agree with this sentiment, but as far as I can tell she has not made it central to her campaign.

Woody: What aspect of US foreign policy do you think they'd be most able to reshape if they're elected?

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Bessner : The US president is able to exert enormous influence on the direction of US foreign policy. Frankly, the issue of most concern to me right now is the fact that, when it comes to foreign policy, the US president has essentially become a king in all but name.

Since the modern foreign-policy-making bureaucracy was created in the National Security Act of 1947, foreign policy has become increasingly centralized in the White House. My primary hope is that, if a Democrat wins in 2020, she or he will devote themselves to restricting the power of the imperial presidency and empowering other constituencies, most notably Congress and even ordinary Americans.

Simply put, I hope the next Democratic president undertakes a number of organizational reforms that reconsider institutions like the National Security Council, Central Intelligence Agency, and Department of Defense. The national security architecture we're living with was created in a very different context the early Cold War to combat a very different threat the Soviet Union.

As Sanders has so compellingly argued, the two major threats to our security today are climate change and global inequality, and I doubt that the institutions we presently have will be able to meaningfully address these global problems. The structure of foreign-policy-making is an area over which the president can have direct, meaningful, and long-lasting impact, and I hope whoever wins seizes the opportunity to change how foreign policy is made.

Woody: Are there questions you think they still need to answer about their respective foreign-policy visions, or issues they still need to address or clarify?

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Bessner : The primary issue that both Sanders and Warren need to address is their position on the United States' global posture.

Presently, the nation controls approximately 800 military bases and regularly intervenes in the affairs of foreign nations. I would like to hear what both Sanders and Warren think should be done about this "pointillist empire" (term I borrow from the historian Daniel Immerwahr ).

Should the nation draw down its military forces? If they believe it should, how do they plan to do so? These are crucial questions about which there should be significant public debate.

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