States pursue their own interest, and are always at risk of being attacked by other countries, wrote Thomas Hobbes in the 17^th century. With the rise of populist impulsive leaders, the world does indeed seem like an increasingly unstable place. We asked Harvard professor of International Relations Stephen Walt about why threat matters more than power, how Trump’s foreign policy is challenging international alliances, and how we created rules to make cooperation easier but have not found a way to prevent conflict where the road is paved with unfriendly intentions. Sitting firmly in the realist school, as he puts it, Walt is concerned with explaining how the world is, rather than how it should be. – Paula Erizanu

PE: What were your first thoughts when you read about the US agreement with North Korea, and Trump’s recent declarations accusing Western allies for abusing the US through tariffs at G7?

SW: There isn’t really much of an agreement between North Korea and the United States. The meeting in Singapore was long on theatre but very short on substance. The North Koreans made no firm commitments to do anything or refrain from doing anything and in a sense the US made a concession offering to suspend military exercises with South Korea – something we did, by the way, without consulting the South Koreans. This got a lot of attention but ultimately was largely meaningless. Trump to some degree got played by the North Koreans because he was more interested in the spectacle than in getting serious about trying to work out our differences. 

In terms of G7, I think it was irresponsible behaviour on Trump’s part to engage in what was essentially a fit of peak over the fact that he was getting some pushback from our allies. To have treated these countries and their leaders with almost personal contempt was very short-sighted diplomacy as it’s going to encourage these countries to do less and less to keep the United States happy because this doesn’t seem to be working.

PE: Realism doesn't put emphasis on personality. Does Trump's outburst at G7 specifically, and his erratic behaviour more generally, then not have considerable consequences for IR? 

SW: There’s no question that realism as a theory of world politics does not place much emphasis on personality. It tends to focus much more on balances of power, distribution of capabilities, what states want and the absence of security protection in the international system. But realism still has some things to say about what happens when a leader like Trump comes along. 

There are two things I would emphasise. First of all, the US has more latitude in foreign policies than almost any other country in the world. We’re very powerful, wealthy, quite secure in the Western hemisphere, which means there’s a very wide range of choices available to an American president and to his aid. That means that when you get an unusual President – and he is certainly that, he doesn’t have to worry as much about what the rest of the world is going to do, at least in the short term. In that sense, realism can help you understand why someone like Trump can get away with any kind of behaviour. 

The second thing that realism would tell you is that it is a competitive world, other states have their own interests and they are going to protect these. Over time, you’re going to pay a price for this behaviour. You’re going to lose out on economic deals that you might have made, alienate allies whose support might have been valuable, encourage other countries to make arrangements that exclude you, even if you are the US. 

So realism can help you see how the system might react to a particularly unusual or irresponsible figure.

PE: The realist school pursues the Hobbesian idea that countries are in a ‘state of nature’. Yet since the 17^th century, we’ve had a number of international agreements and organizations developed to help ensure peace. But would you say that their fragility means that, internationally, states are still in a ‘state of nature’?

SW: The basic idea behind realism which you do see in Hobbes is that in the absence of a world government that could protect states from each other, all countries have to worry about the possibility that they might get attacked. Wars don’t happen all the time, they are not constant but we have to worry about them. In other words, it is a self-help system in which each state is responsible for its own protection and security and that does create the danger of conflict, which never completely goes away.

Since Hobbes wrote, we’ve seen the emergence of all sorts of international organisations, the increased expansion of international law, the development of the UN, World Bank, World Trade Organisation, hundreds of agreements and regimes. And those do help regulate world politics. They facilitate cooperation between states that want to cooperate. For instance, countries that want to trade and understand that there have to be some rules about how to cooperate with each other.  

But those organisations cannot prevent states from quarrelling when they do disagree, and they can’t keep states from fighting if they decide they want to. None of these organisations could stop the US from invading Iraq in 2003, none of them stopped Russia from taking Crimea, or Saudi Arabia from attacking Yemen. There are real limits to what these organisations can do and that’s why states still have to worry about security, war, and develop armaments, armies, and alliances to protect themselves. 

PE: One of the major challenges in IR, and specifically with the agreement with North Korea, for instance, is to distinguish between discourse and deeds. How can international agreements be taken seriously, if they are so often broken?

SW: It’s important to recognise that agreements also get kept, primarily because it’s in the countries’ interest to keep those agreements. For example, there is an international agreement that regulates commercial aviation. That agreement gets enforced because it’s in every country’s interest to abide by it. 

The key to understanding this is that almost any international agreement has to be in both parties’ interest. If you don’t provide for each party’s interest to be met, then one party’s going to be resentful. So the most robust agreements that do last tend to suit everybody’s interest, have a capacity to be revised over time, they often have a dispute resolution mechanism built into them. Once one side thinks that the other is cheating, they can adjudicate it. These are all ways to make international agreements more robust while recognising that they’re not going to last forever, conditions change, countries are going to look for ways to revise or get out of an agreement that is no longer in their interest.

PE: Does the realist perspective assume that, in always pursuing their own interest, states are rational actors? For instance, in Trump's case with G7, or in Russia's case of putting military power over economic wealth, it seems like neither actor has pursued their country's actual long term interest. Might this be compared to the criticism behavioural economics brings to classic economic theory?

SW: Yes. Realism tends to assume that states are rational, or at a minimum, ‘sensitive to costs’ and generally acting strategically. Of course, realists understand this is not always the case. Very powerful states can sometimes get away with irrational behavior—though they will still pay a price.  Realists also recognise that there is lots of uncertainty in world affairs—in particular, it is hard to anticipate other states’ behavior in the future—and so even highly rational states sometimes miscalculate and end up doing things that they think will be beneficial but turn out not to be.

PE: You are known for coining the balance of threat theory, in response to the classic IR balance of power theory. What does it entail? 

SW: The balance of threat theory says that states respond to threats. Threats are made of a combination of power, proximity, offensive capabilities and perceptions of intent. If you think another country has more ambitious or hostile aims, you’ll regard them as more threatening. If a country has military forces that aren’t good at going to other countries – that’s less threatening than a country who is ready to go all over the world to threaten other countries. 

PE: How does it apply to the US-North Korea relationship?

SW: If you think about North Korea and the US, that’s a perfect recipe for trouble. North Korea is not a world power but it does have some military capabilities that threaten our ally South Korea and possibly other neighbours, and its development of nuclear weapons is regarded as something threatening to us as well. North Korea has also attacked South Korea in the past, assassinated South Korean politicians, which makes it seen as an uncooperative state and a threat.

Now of course North Korea views us very much in the same way. We have a lot of military power in Asia. They believe the US would like to see their government collapse. And for these reasons, they regard the US as the threat.

The only way to change that relationship is for each side to take sufficient steps to reassure the other that it is not as dangerous as we once thought. That is what I think the Trump administration would like to see happening and the question is whether they will be able to pull it off.

PE: What would be the means to achieve substantial change in the US-North Korea relation?

SW: The United States and North Korea would have to negotiate detailed agreements to end North Korean nuclear and testing, stop further enrichment of fissionable material, and freeze North Korea’s existing nuclear arsenal at its present level. They would also have to agree on arrangements that would permit independent verification of all of this.

PE: Beyond the military and the political, how does economic and cultural globalisation feature in International Relations?

SW: I’d say three things. First of all, since the 1970s, IR has recognised that a world that was becoming more interdependent - where trade, investment and the movement of people were becoming more frequent - required rules. Second, in the last decade or so, there’s been a growing realisation that while globalisation has had many benefits, it’s also had many downsides, inside and between countries. It’s created a more fragile world order as disadvantaged groups reacted politically. Globalisation did not necessarily have to be reversed but maybe slowed down and dealt with in different ways. 

The final point I will make is that a world in which international corporations operate is still a world whose basic parameters are set by states. It’s a world negotiated between national governments, and enforced by them so it’s still international politics which are likely to influence how international corporations operate and I don’t think that’s likely to change anytime soon. 

PE: But does the international balance of power and threat change through global economic tools, such as wage and taxation levels and incentives for corporations?

SW: In my view, these measures do not have much impact on the balance of power/threats, except insofar as they affect a country’s long-term economic development and thus its overall latent power.

PE: Feminist and post-colonial perspectives have challenged realism in IR. Do you find these perspectives helpful?

 Although I am firmly in the realist school I like having a diverse intellectual culture. A number of feminists and post-colonial perspectives have brought new insights and arguments. Ultimately, the value of any perspective lies in what it allows you to understand and explain about the world that we live in. Does it allow you to predict events? This is an incredibly complicated world that we’re all trying to understand through simple tools and theories. I tend to favour realism because I think it gives me the most explanatory power. But it doesn’t explain everything. 

A feminist perspective can lend some additional insights. For example, governments where the representation of women is higher across the board (not just in terms of who’s Prime Minister) tend to to be less conflict-prone and more inclined to make and keep peace agreements, for example. Countries where there’s a high disparity between the number of males and females, sometimes called surplus males, may have some foreign policy effects encouraging greater adventurousness and aggressiveness.

PE: And what are your views on the recent revisions of the concept of security, to include different threats such as terrorism, environmental issues and humanitarian crises?

SW: I’ve been wary of broadening the label of security or international security to include every possible threat to human beings because it tends to make the concept so big that it becomes meaningless. 

I think one category would be technologies and things that countries or terrorist groups can use to harm other people. The second basket can be changes to the environment where people live – from climate change to epidemics. And the third basket could be local issues – for instance, here in the US the greatest threat we face is not from other countries but from the lack of gun control and the fact that some 30,000 Americans are killed by gun by other Americans. I would keep these separate from the international security concept. 

Editor's note: Anastasia Broder contributed to this interview.