The G-20 summit in Hamburg, Germany wrapped up last week. Leaving aside the fallout from Trump’s first face-to-face meeting with Russian President Vladimir Putin, the headlines that emerged were dispiriting to say the least. Some White House officials apparently see the trip as a success, given some positive feedback on the president’s pre-summit speech in Warsaw. What’s more, according to the New York Times, protests at the event were not aimed at his presence but rather at globalization more generally—a sentiment Trump and the anarchists that march at every G-20 share. Yet the results of the summit are largely being viewed as further evidence of America’s diminished leadership in the world during the short tenure of the 45th president. And while other issues have garnered more attention, the summit could have long-term implications for international security.

A great deal of post-summit attention has been on the role of trade in the talks, but the discussion centered mostly on the emergence of new trading blocs and potential retaliatory trade restrictions. President Trump famously ran on a protectionist campaign platform that viewed global trade as a zero-sum game at which the United States was losing. Before the summit even began, Japan and the European Union responded to Trump’s protectionist threats by announcing their own trade agreement.

During the summit, administration officials continued to threaten restrictions on steel imports—claiming there is a “global steel glut” and alleging that China is undercutting the American steel industry by subsidizing its own. While world leaders agreed to look into the matter, there was also talk of a “global trade war” ensuing should the White House place tariffs on steel imports—with retaliatory measures coming in the form taxes on American bourbon. The Washington Post summed up the mood following the meeting: “But even in areas of nominal compromise, such as trade, top European leaders said they have little faith that an agreement forged today could hold tomorrow.”

That last line could be particularly significant for international politics in the coming years. While economists rightly warn that trade restrictions like the ones the Trump administration is floating will cause more harm than good domestically, they could also damage national and international security. As I previously wrote, international trade is an important factor in determining the chances that states will go to war.

Moving beyond simplistic notions about soldiers crossing borders when goods fail to—notions that animated liberal ideas about the relationship between trade and war and peace for centuries—political scientist Dale Copeland has found that it is positive expectations of future trade, rather than current or past levels, that determine the likelihood of whether states will go to war or not. Even if past or current levels of trade are low, when states believe they can benefit from trade with one another in the future, they are less likely to go to war. Conversely, even if current levels of trade are high, if state leaders do not expect to benefit from trade with one another in the future, they are more likely to consider “hard-line measures”—including war—to secure their long-term interests.

War is not the inevitable outcome of the lack of faith world leaders have in their ability to forge a lasting agreement on trade with the Trump administration. But diminished expectations of future trade as a result of protectionist policies—both in the United States and abroad—could lead to increased chances of war. When these diminished expectations are coupled with the fraying of long-standing multilateral political relationships, the probability of conflict is likely to increase further. While the diminishment of American leadership and kowtowing to Vladimir Putin might garner the most headlines, the most significant long term consequence of the G-20 summit might be a world in which the chances of war are higher than they were before.