Conspiracy theories can significantly influence public support for war

A large-scale international study suggests that conspiracy theories about foreign governments can meaningfully shape public attitudes about war—even among people whose countries are not directly involved in the conflict. The research provides evidence that believing such theories tends to increase support for military aggression, reduce humanitarian concern for the enemy, and heighten perceptions of threat. The findings were recently published in the European Journal of Social Psychology.

Throughout history, conspiracy narratives have often been used to justify war. From Adolf Hitler’s claim that communism was part of a Jewish plot to Saddam Hussein’s suspicion that Iran conspired to incite revolution in Iraq, such beliefs have served as powerful political tools. The Russian government’s rationale for invading Ukraine—framing it as a mission to “denazify” the country and stop alleged genocide against ethnic Russians—follows a similar pattern.

While the presence of conspiracy rhetoric in wartime politics is well established, the question of how such narratives influence public opinion has received less empirical attention. The authors of the new study sought to fill this gap by systematically examining whether and how conspiracy theories about foreign nations impact support for war, sanctions, aid, and group identification.

They reasoned that conspiracy theories often contain strong intergroup components, portraying another group as secretly plotting to cause harm. This framing may evoke fear, justify aggression, and diminish empathy, making conspiracy theories particularly effective at shaping wartime attitudes.

“Political leaders often justify waging war with conspiratorial rhetoric. A recent example is Putin, who claimed that the Ukrainian government is a regime of Nazis that commits genocide on Russian minorities,” explained study author Jan-Willem van Prooijen, head of the Social Psychology Section at VU Amsterdam, senior researcher at the NSCR, and endowed professor of radicalization, extremism, and conspiracy thinking at Maastricht University.

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“This was not an anomaly: Throughout history conspiracy theories often have been part of the motivation to wage war. When Hitler invaded the Soviet Union in 1941, he believed that communism was a Jewish conspiracy for world domination. Also democratically elected leaders can justify war with conspiracy theories. Think of George W. Bush, who in 2003 claimed that Saddam Hussein was hiding weapons of mass destruction. Our central research question was: To what extent do such conspiracy theories influence public opinion, by making people more supportive of war?”

The research included five core studies and one pilot, using both longitudinal surveys and controlled experiments to assess the psychological impact of conspiracy theories.

In the first two studies, conducted in Greece and Slovakia, the researchers used two-wave panel surveys to examine beliefs about the war in Ukraine. Study 1 included 646 Greek participants in the first wave and 513 in the second. Study 2 involved 900 Slovakian participants initially, with 690 completing both waves. In both samples, participants were asked about their agreement with conspiracy theories that portrayed Ukraine and its allies, particularly the United States, as secretly orchestrating aggression.

The results showed that higher belief in these conspiracies at the beginning of the study predicted increased support for the Russian invasion and reduced support for Ukraine-related aid and sanctions two months later. This pattern held after controlling for prior attitudes, suggesting that conspiracy beliefs had a meaningful influence over time.

In a third study, the researchers tested whether similar dynamics applied in a different conflict. A total of 1,007 participants from the United States, the United Kingdom, the Netherlands, and Greece were surveyed in the weeks following the 2023 Hamas attacks in Israel, with 849 completing the second wave.

Participants who endorsed conspiracy theories about the Israeli government—such as the belief that it allowed or staged the attacks for political gain—tended to show increased support for Hamas over time. These beliefs also predicted greater identification with Palestinians and reduced support for Israeli civilians, suggesting a broad influence on war-related attitudes.

In the fourth study, 600 American participants were randomly assigned to read either a conspiratorial narrative about Ukraine or a neutral historical account. A fifth study extended these findings to a fictional context, using a vignette about a made-up war between two imaginary nations, with a sample of 803 U.S. participants.

The experimental studies supported a causal interpretation. In Study 4, participants who read a conspiratorial narrative about Ukraine expressed higher support for Russia’s invasion than those in the control condition.

In Study 5, participants who read about a fabricated conspiracy involving chemical weapons were more willing to support war and less inclined to provide humanitarian assistance. Importantly, this study also found that perceived threat from the alleged conspirator mediated the relationship between conspiracy exposure and attitudes, suggesting that these beliefs change how people appraise risk and justify aggression.

“Previous studies has underscored that conspiracy theories can increase intergroup hostilities, as reflected in prejudice, radicalization, and even violence,” van Prooijen told PsyPost. “Our findings suggest that also at a geopolitical level conspiracy theories may have an impact, as they can influence public opinion about wars.

“Exposing people to such conspiratorial rhetoric causally increases their support for war. Moreover, we found similar effects on a range of other relevant variables, such as support for sanctions, humanitarian support, and military support. Apparently, conspiracy theories are effective in increasing public support for war.”

The researchers also found evidence that conspiracy beliefs and support for war can reinforce each other over time. The longitudinal studies found that conspiracy beliefs about Ukraine and its allies predicted increased support for the Russian invasion, greater identification with Russia, and reduced support for sanctions and aid to Ukraine over time. But the reverse was also partially true: participants who initially supported the invasion or opposed aid were more likely to endorse conspiracy theories about the United States in later waves. A similar pattern emerged in the Gaza-related study—support for the Hamas attacks predicted stronger conspiracy beliefs about Israel over time.

“What was interesting is that we also found some support for another process: To some extent, people may rationalize their existing support for a war by endorsing conspiracy theories,” van Prooijen said. “This finding was less consistent across measures, but still clearly visible in the data. This suggests that to some extent, people may use conspiracy theories to legitimize the harm they see happening to another group.”

But as with all research, there are some limitations. “Due to logistic reasons, all our studies were conducted among participants from countries that were not fighting themselves,” van Prooijen noted. “We had samples from the United States, Greece, Slovakia, the United Kingdom, and the Netherlands. This is still quite valuable: After all, also in these countries important political decisions relevant for wars (e.g., Ukraine and Gaza) depend on public opinion, such as support for sanctions, or providing humanitarian or military support.”

“Still, an open question is how the people most directly affected would respond to these conspiracy theories. What would happen if we conducted our studies among for instance Ukrainian or Russian citizens? This is currently still an open question.”

“While it is clear that conspiracy theories influence support for war, more work is needed to establish why this is the case,” van Prooijen continued. “We found some preliminary evidence that conspiracy theories can make another group seem threatening. This might imply that due to conspiracy theories, aggressor groups may wage war out of the belief that they are defending themselves. But more research is needed to establish this idea empirically.”

“There is a clear practical implication of this finding: Which is that political leaders who want to wage war (for whatever reason) can use evidence-free conspiracy theories strategically to shape public opinion. This makes conspiracy theories a cheap and potentially dangerous tool in the hands of political leaders who seek to gain support for impending military aggression.”

The study, “The Evil Enemy: Belief in Conspiracy Theories Predicts Attitudes to War,” was authored by Jan-Willem van Prooijen, Kyriaki Fousiani, Jakub Šrol, Vladimira Čavojová, Ana Clara Kaneko Ebert, Emel Müller, and Ece Sağlam.