Sen. Bernie Sanders is running for president again, and this time around he plans to be much more vocal about foreign policy.

Matt Duss, Sanders' foreign policy adviser, spoke with INSIDER about the senator's global affairs priorities. Duss also addressed some of the criticism Sanders' received in 2016 for a perceived lack of vision regarding foreign policy.

"Coming out of 2016, we recognized that he had a much bigger platform, a much bigger opportunity to move things in a progressive direction and the importance of making foreign policy part of that, which is why he asked me to join the staff," Duss said.

Duss pushed back on recent attacks from Democrats against Sanders' stance on the Venezuela crisis: "No one is defending Maduro — the senator certainly is not doing that."

He also touted Sanders' efforts to end US involvement in the Yemen conflict, and expressed optimism about the fate of a resolution the senator is spearheading on the matter.

If Sanders is elected, Duss said we'll see more dialogue between the US and its global adversaries: "We don't have to fear sitting down with anyone."

It's been less than a week since Sen. Bernie Sanders announced he's running for president again and he's already dominating headlines about the 2020 race in a broad, diverse field of candidates.

Sanders in 2016 went from being a relatively obscure leftist figure to a household name and one of the most popular politicians in the country. His campaign for the presidency was ultimately unsuccessful, but he left his mark on both the Democratic Party and the country by making ideas previously considered radical in the realm of US politics fairly mainstream.

But as Sanders was frequently criticized in 2016 for having a somewhat jumbled approach to foreign policy. Early on, his campaign website didn't have a foreign policy section, and he stumbled on the topic during presidential debates.

Since 2016, however, Sanders has dedicated a significant amount of his time and energy to global affairs.

He's delivered two major speeches on foreign policy, one at Johns Hopkins School of Advanced International Studies in October 2018 and another in September 2017 at Westminster College — where Winston Churchill gave his infamous "Iron Curtain" speech.

Sanders is also leading the charge on a Senate resolution to end US support for Saudi Arabia in Yemen.

Read more: Senate rebels against Trump, moves to withdraw US support for Saudi Arabia in Yemen in historic vote

Matt Duss, 46, has been at Sanders' side as his foreign policy adviser throughout this shift, and he'll be helping the senator craft his approach to global affairs along the campaign trail.

Matt Duss (center) back in his days as a blogger in 2010. He's now advising Sen. Bernie Sanders on all things foreign policy. Isaac Brekken/Getty Images

Duss, a staunch progressive who broke into the political world as a blogger, has gained prominence among left-leaning foreign policy wonks and added significant credibility to Sanders on matters of global import.

Read more: Bernie Sanders slams US support for 'despotic' Saudi Arabia in Yemen and bashes Trump over Khashoggi: 'No more! Enough death. Enough killing.'

Sanders' bold approach to domestic politics is reflected in his views on foreign affairs, which at times makes him a fringe figure in Congress. In recent days, for example, he's been criticized by some congressional Democrats for not recognizing Juan Guaidó as Venezuela’s legitimate leader and for not referring to Nicolas Maduro as a dictator.

Duss spoke with INSIDER last week, offering an intimate view into how Sanders sees the world and what the senator will be prioritizing along the campaign trail. He also addressed the criticism Sanders has received on the subject of foreign policy, and why he feels much of it is unfounded.

Editor's Note: This interview has been edited for length and clarity.

INSIDER: Sanders faced a fair amount of criticism in 2016 for not having a clear foreign policy vision. How has Sanders evolved since and has he made it more of a priority?

Duss: He certainly has made it more of a priority. There's a great deal of evidence for that, not only in the statements he's made, speeches he's given, but also substantively and legislatively. The Yemen war powers resolution is the most prominent example of [Sanders] being more aggressive on the issue of foreign policy and adding it to the progressive agenda.

Coming out of 2016, we recognized that he had a much bigger platform, a much bigger opportunity to move things in a progressive direction and the importance of making foreign policy part of that, which is why he asked me to join the staff.

INSIDER: There are strong anti-interventionist sentiments on both sides of the aisle right now. Barack Obama was fairly critical of the US in a similar way back in 2008, but faced accusations of being unpatriotic as a result. Could Sanders face similar attacks?

Duss: He certainly will. We're seeing it right now with some of the attacks he's getting even from some Democrats on Venezuela.

But there are shared concerns amongst progressives and conservatives about American militarism, the costs, and many unintended consequences of this kind of interventionism that has guided our approach certainly since 9/11, but even before that.

The Yemen resolution, the fact that [Sanders] introduced it with Republican Mike Lee as an original co-sponsor as well as Democrat Chris Murphy — that's an illustration of this, right? Sen. Sanders and Sen. Lee don't agree on a great deal, but they strongly came together around this idea that not only do we need to take a hard look at some of these interventions we're supporting, but we also need to take a hard look and reassert Congress' constitutional authority over these interventions.

This is where you see a sharp difference between Trump's approach and Sen. Sanders' approach. Trump and a lot of the conservatives who support him see international relations in very zero-sum terms: If someone else is winning the US is losing; the US needs to dominate all these relationships.

Sen. Sanders does not see it in those terms, he sees it in very much a positive-sum way: We can all gain when we are working together, multilaterally. We have shared problems and challenges, so we need shared solutions.

INSIDER: You recently told The Nation what it meant to you when in 2008 you heard Obama say he didn't just want to end the Iraq War, he wanted to end "the mind-set" that got the US into the war in the first place. But once he entered the White House, Obama encountered a reality that made it difficult to deliver on his campaign's idealistic foreign policy vision. If elected, could Sanders face a similar reality as president?

Duss: That statement [from Obama] meant a lot to me and a lot of other young progressives that I know for a reason — it really captured something.

But let's remember that when Obama came into office he had a financial crisis. There was a lot going on and Obama had an idealistic idea of turning the ship on a number of things, including foreign policy. I don't ding him too hard for some of the decisions he made, they made a great deal of sense at the time. In retrospect, some of the decisions led to really problematic outcomes now, such as the decision not to investigate fully the use of torture or other things like that.

Any president has to deal with the world as it is when they take office. But what Sen. Sanders recognizes is building that kind of movement around this idea, and starting a much more robust conversation and a real political consensus about what America's role in the world should be.

Now that's challenging, right? Because foreign policy is not something that is very immediate to a lot of Americans for obvious reasons, but grounding it in this discussion about how we treat ourselves, how we treat our own society, what kind of society we want it, how that is reflected in our foreign policy is the way to go about it.

INSIDER: Congress essentially abdicated its war-making authority with the Authorization for the Use of Military Force (AUMF) in 2001 — which has since allowed presidents to wage an expansive, ill-defined, global war on terrorism with few obstacles. Will Sanders call for repealing the AUMF along the campaign trail?

Duss: He will be focusing on that. He has said that Yemen is important in itself because it's a humanitarian crisis. The US shouldn't be supporting the Saudi coalition.

There's the constitutional question of congressional oversight and of reining in these wars, and that relates to the broader set of issues about the 2001 AUMF and the global war on terror. He will be talking about these things.

INSIDER: Does the Yemen resolution have a realistic shot in the Senate? Does Sanders' forceful criticism of Trump jeopardize the fate of the resolution?

Duss: It does have a realistic chance. We have 51 of the 56 who voted with us in December — they're still in office. Plus we have two new members of the Democratic caucus, both of whom have indicated that they will vote with the caucus, which puts us at 53. We only need 51 votes to move through every stage of this process.

The Trump administration will put a lot of pressure on Republicans to peel off this thing. But it's the same resolution that passed two months ago. The humanitarian crisis [in Yemen] has only gotten worse.

INSIDER: Sanders' criticism of Israel, particularly on the debate stage in 2016, is notable for multiple reasons. He's Jewish and less susceptible to accusations of anti-Semitism. But it's politically risky. Does Sanders want to radically alter the US-Israel relationship or is he more concerned with the rights of Palestinians and related humanitarian issues?

Duss: I don't think he wants to radically reorient the relationship. He's been clear he supports Israel's right to exist, he supports the two state solution.

But going back to that debate you mentioned, his point about [Israeli Prime Minister Benjamin Netanyahu] has been borne out many, many times. We just saw this week with Netanyahu literally forming an alliance with fascists, people who are identified as terrorists.

But the approach [Sanders] would support, and has supported, is one that is consistent with our relationships with other countries, which is to say: we support the rights of Israelis and Palestinians to live in security and dignity. And we have to recognize when policy, for example the settlements or the occupation, undermine those goals. So the US needs to speak clearly about that and when necessary we need to take steps to put pressure to stop those policies. [Sanders is] going to be willing to do that.

INSIDER: Sanders has been accused of being too soft on dictatorial leaders like Fidel and Raul Castro, Daniel Ortega, and more recently Nicolas Maduro. Is any of this criticism fair?

Duss: There are times where he's definitely pushed back on some of the reflexive hawkishness of the establishment. But he's always been consistently for human rights and self-determination.

His statement on Maduro, if you go back to what he initially said, reflects that. He's very clear about Maduro's abuse of his population and the corruption.

But that doesn't mean that we endorse Trump's approach here. It's making sure that the approach is consistent and grounded in a set of principles — human dignity, human security.

INSIDER: Sanders is also facing criticism for not recognizing Juan Guaidó as the legitimate leader in Venezuela, including from Democrats in Congress, as the US and many of its allies take a stand against Maduro. From the senator's perspective, how should the US approach the crisis in Venezuela?

Duss: No one is defending Maduro — the senator certainly is not doing that.

But coming out as Trump has done and sort of putting the US in the lead — just completely recognizing Guaidó as the president — and putting the US four-square behind the opposition, has the potential to create some possible outcomes that the US is not quite prepared for.

There are also other people the US could be talking to. It's unfortunate that the Trump administration did not pursue the opening with Cuba that the Obama administration started, because talking to Cuba right now could actually be really useful.

INSIDER: That's an interesting point because Trump is clearly open to dialogue with North Korea, and has defended the notion of talking to your enemies, even as he went after Obama over reopening dialogue Cuba and Iran. What's Sanders' view on this?

Duss: Sen. Sanders was perhaps the only member of the Democratic office to actually compliment Trump's last summit with Kim Jong Un for that reason. Talking is better than threats.

INSIDER: So, if we ultimately have a President Bernie Sanders, would we also see more dialogue with America's geopolitical adversaries?

Duss: We certainly would. We'd be clear about the values and the outcomes the US favors — self-determination and human rights, respect for people's dignity and their security.

But the fact is the US is extraordinarily powerful and we don't have to fear sitting down with anyone, whether it's the North Koreans, whether it's Iran, whomever.

INSIDER: Trump has a record of praising dubious world leaders and Sanders has referred to the president as an "authoritarian." Do you agree with the senator?

Duss: [Trump] is certainly behaving in authoritarian ways. There's some ways in which he is being constrained.

But certainly using the bully pulpit, the huge megaphone that he has on Twitter and elsewhere, to attack the press, to attack progressives, to attack all kinds of people — these have consequences.

We've seen violence against the media. We saw this guy who was just arrested planning this huge attack.

Leaders in other countries take notice of what the president of the US says. In talking to activists in other countries, there is no question in their mind that they feel that their oppression and [their leader's] use of these tools to control, oppress, and persecute their own people is being affirmed by the president of the US. That's a huge problem.

INSIDER: If you had to summarize Sanders' worldview as succinctly as possible, what would you say?

Duss: He sees the US as a kind of global facilitator by virtue of our enormous economic, diplomatic power. The US has the ability to bring parties, states, and people around tables to address common challenges that really no other country has.

That doesn't mean that the US needs to run to the head of every parade or be in charge of everything — certainly not. But the US does have a role to play in facilitating multilateral cooperation, conversation, and innovation.