Five Questions on Defense Cooperation Agreements

What are defense cooperation agreements (DCAs)? Why look at DCAs rather than alliances?

Alliances have been around since at least the 5th century BC, when one led by Athens and another led by Sparta fought each other in the Peloponnesian War. Today, when I ask my undergrads about defense cooperation, they immediately think of the NATO alliance, which forms a crucial part of the international security architecture.

But the problem with focusing on alliances in international security studies is that most are just dormant. An alliance is a binding legal commitment for mutual defense between at least two countries to deter others from attacking, but as long as the agreement does that, it never gets activated—it just sits there. NATO is unusual in the peacetime activities members engage in outside of the alliance. But of the alliances that currently exist, only 10–15 percent mandate any form of peacetime activity. The vast majority do not—they just deter.

Think of alliances as passive agreements, whereas DCAs are active. The point of a DCA is to engage in routine forms of day-to-day defense cooperation, like promoting research into new types of military technology, facilitating arms trade, and conducting joint military exercises and contributions to peacekeeping operations.

It’s not that one is more important than the other—they do different things. DCAs have become increasingly visible because they’re all over the place now. Back in the 1980s, it was mainly the United States and Soviet Union signing DCAs with a handful of countries. Then, in the 1990s, a lot of post-Soviet and Eastern European countries started signing these agreements to improve their military capabilities now that the Soviet Union was gone.

Fast forward to the 2010s and 2020s, and everybody is signing DCAs—hundreds each year. They often contain boilerplate language saying this agreement isn’t targeted at any third party to avoid provocation. For example, before the current hostilities unfolding in the Middle East, Russia and Iran would sign agreements that claimed they weren’t directed toward any third party to avoid provoking Israel.

The question is: do these agreements create pseudo-alliances of countries that all have DCAs with each other? Member states are not all agreeing to come to one another’s defense, but they’re still doing things like selling weapons, building new technologies, and conducting joint military exercises that could create the sort of in-group, out-group dynamics we see with alliances.

The paper looks at the network dynamics behind DCA effectiveness. Can you explain why you’ve looked at common third-party relationships and how they influence defense cooperation?

There’s a tendency to look at treaty effectiveness in terms of whether treaties can be enforced or whether countries are punished for breaking the rules. But this paper focuses on the influence of network dynamics, the “friend-of-a-friend” relationships between states with DCAs.

In networks, third-party effects are an important influence. In a social network, for example, you and I might not know one another, but if we have a friend in common, that increases the odds that we’ll end up meeting at some point and become friends. That’s the classic “friend-of-a-friend” logic.

In international relations, it’s a bit different. Countries are all aware of one another’s existence—they don’t need a third party to introduce them to another country. Instead, the argument is that third-party connections lead to changes in their policies.

In defense, that is seen in matters like the kind of aerial refueling technology a country uses. There are only two types of this technology. If the United States and Japan want to hold joint military exercises, they want to be able to refuel one another’s aircraft, and so they need to use the same technology. The same goes for things like ammunition standards and fuel mixtures.

There are many ways that countries need to line up their defense policies to cooperate with one another. After the Cold War, the United States encountered challenges cooperating with newly independent countries in Eastern Europe. These young democracies wanted to cooperate with the West, but they were using old Soviet equipment, making it hard for them to use newer equipment produced by the United States, Britain, or France.

At a practical level, cooperation is often limited by a country’s policies—not just in defense but in a lot of different areas as well. Economic cooperation might be limited if investors from country A can’t invest in country B because those transactions aren’t compliant with country A’s labor standards, environmental standards, or anything else. So, policy is crucial to facilitating cooperation.

The argument in the paper is that when two countries have mutual ties to the same third party, their policies come into closer alignment. We see a lot of examples, often quite intentional.

One of the key reasons that Georgia and Azerbaijan, for example, cooperate with Turkey on defense is that Turkey is a NATO member state. Therefore, bringing their defense policies into alignment with Turkey brings them closer to the U.S. and Western European standards of every other NATO member state. This was a strategy that Ukraine pursued very explicitly after the Cold War, as it looked for U.S. allies to cooperate with as a steppingstone to direct cooperation with the United States.

There’s a long history in East Asia of a hub-and-spoke cooperative system where the United States was the hub of the system, cooperating with all the spokes individually, like Australia, Japan, the Philippines, and South Korea. That means that those countries are using U.S. military equipment and are used to U.S. military training standards and operational protocols. That now makes it easier for Australia, Japan, the Philippines, and South Korea to cooperate with one another. And these countries are signing defense agreements and engaging in higher levels of defense cooperation because of this common history of cooperation with the United States.

How did you test this theory of how “friend-of-a-friend” relationships impact defense cooperation?

Network methodologies are increasingly used in international relations because relations between countries are like a social network. Everything influences everything else. We can’t treat U.S.-Mexico trade flows as an independent datapoint because if U.S.-China trade goes down, U.S.-Mexico trade will tend to go up. We have to grapple with the reality that our datapoints are all interdependent, and that turns out to be extremely challenging.

There are intricate and complex network models, but I use a pretty straightforward approach in this paper, which is to see whether a given pair of countries, say Japan and Australia, are engaging in high levels of defense cooperation, which we can measure in terms of things like joint peacekeeping operations or arms trade. The primary independent variable that I’m interested in is how many third parties they have defense cooperation agreements with—basically, how many friends of friends do they share in common?

The United States is the most prominent third party in these relationships, but it’s not the only one. When it comes to measuring these relationships, it’s literally a matter of counting triangles, where the bottom two points on the triangle are, say, Australia and Japan, and the top point of the triangle would be some third party that they both cooperate with. It turns out that the number of third parties they are cooperating with directly influences how much actual cooperation they engage in themselves.

Beyond defense cooperation agreements, how applicable is this research to other sorts of bilateral agreements?

The logic is applicable to virtually any form of cooperation where countries need to coordinate their policies. In other words, we should think of international cooperation as fundamentally about policy coordination.

DCAs are essentially one way of looking at the big picture of how treaties actually achieve their goals, and why some are effective and others ineffective. And we need to distinguish this from compliance with treaties. For example, if countries sign environmental agreements pledging to reduce greenhouse gas emissions by 50 percent but only cut emissions by 25 percent, they’re not in compliance with the treaty—but the treaty was still effective at reducing emissions by 25 percent.

Experts in international law tend to care more about compliance, but political scientists care about effectiveness. We want to know if the treaty did something, if it changed a country’s behavior versus not signing it.

The finding generalizes into economic issue areas as well. In a preferential trade agreement, for example, the goal is to increase trade flows, so countries sign an agreement to reduce trade barriers, lower tariffs, and implement other policies which should lead to higher volumes of trade. And it turns out the success of that depends on how many third parties are involved in these relationships: the more third parties there are, the higher the overall trade flows. The same applies to investment treaties—the more third parties that you have bilateral investment treaties with, the higher the resulting level of foreign direct investment.

The bottom line is that countries have all these rules that they need to bring into alignment in order to make a treaty effective. And it’s easier to do that if they’ve already aligned with the same third parties—because they’ve already indirectly pulled their policies closer together.

Your paper has a great quote that says, “international relations are in fact network relations.” With the United States being central to that network, what does Washington’s recent reevaluation of its role in the international system mean for defense cooperation across the world?

There’s a glass-half-full and a glass-half-empty answer to that question. The glass-half-empty response is: these forms of cooperation are not going away. So if the United States is pulling back, that just creates opportunities for other countries—potentially U.S. adversaries—to fill the vacuum.

One of the key mechanisms of third-party influence is what I call “active facilitation,” which means the third party is actively trying to get these countries to pull their policies into closer alignment. There are lots of examples of this, but the one I discuss in the paper is the United States pushing for more defense cooperation between South Korea and Japan, who, for longstanding historical reasons, have generally been resistant to this. If Seoul and Tokyo could share intelligence with each other, that would allow the three partners to coordinate a better common response to the North Korean threat. But if the United States were not trying to push them together, then there could be an opportunity for another power to be that active facilitator, bringing them into closer policy alignment for their own ends rather than those of the United States.

On the other hand, the glass-half-full perspective is that there are other ways that countries’ policies come into alignment without having an active facilitator. For example, Azerbaijan and Georgia want to cozy up to NATO states even if the United States pulls back, because those partners could potentially be a line of defense against Russia.

One of the things to emphasize with networks is that there are all these structural effects that can’t be reduced to one individual actor. Once this structure is in place, it influences the behavior of countries even if there are some that try to go it alone or change their policies.

The cake is already baked—every country in the world participates in defense cooperation agreements, there’s only variation in the extent to which they participate in them. And over the past two decades, there has been so much DCA activity that it’s entirely possible that this cooperation—even cooperation that benefits the United States—will continue to move forward even if Washington isn’t participating in it.

Brandon Kinne is a professor of political science at the University of California, Davis.

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