When US President Donald Trump announced a two-week ceasefire in the war against Iran on Tuesday, he walked back from his threat to “end a whole civilisation” even as Iran remained defiant.While questions remain over whether the ceasefire would hold after Israel continued its aggression in south Lebanon and Iran struck oil facilities in the Gulf nations, Trump’s vacillating statements and inconsistent actions — not just during the course of the war but throughout his second presidential term — have lent credence to belief that the US President is practising the “madman theory”.In foreign policy, the theory gained currency during the Cold War and proposes that heads of state, by showing a willingness to take extreme measures, can influence an adversary’s calculations by raising fears of escalation. Although it was meant to be used to explain erratic or unpredictable behaviour, this was subsequently deployed as a deliberate strategy to intimidate opponents into making concessions.Roseanne McManus, professor of political science and international affairs at Pennsylvania State University, explains how Trump seems to have put the theory into practice since his return to the White House last year, and what it means for the US’s standing in the global order.In the framework of the “madman theory”, how do you place US President Donald Trump’s statements and actions during the course of the war in West Asia?Exactly what it means to be a “madman” is not always clearly defined, but in my research, I argue that two types of “madness” can give leaders’ threats more credibility. The first is unpredictability, meaning that the leader might do anything. The second is extremism, meaning that the leader is insensitive to the consequences of war, including casualties.Trump’s statements and actions during the war could lend support to perceptions that he has both types of ‘madness’. His inconsistent statements about the goals of the war and vacillation between threats and more conciliatory rhetoric give the impression of unpredictability.Additionally, Trump’s willingness to shatter norms and experience domestic and global backlash for making extreme threats, such as to destroy an entire civilisation, suggests an unusual indifference to the consequences of his actions.Story continues below this adHow has Trump’s approach differed from that of former US presidents like Richard Nixon and George W Bush? Or even other world leaders, such as Russian President Vladimir Putin and North Korean leader Kim Jong Un?Overall, I think that Trump has cultivated more of a madman image than most other leaders. According to private records, Richard Nixon desired to cultivate a reputation for madness. Yet he was not consistent enough at acting madly for others to believe it. The Soviets not only did not believe he was mad, but they considered him their favorite US president to work with.George W Bush was called a madman by some critics who used the term for general disparagement, but I don’t think he either sought or had a reputation for either type of madness that I identified above. He was viewed as a hawk, but not necessarily unpredictable or extremist.Vladimir Putin developed a madman image after invading Ukraine, and he sought to convince the West that he was insensitive to the costs of using nuclear weapons. However, I think his reputation for madness faded a bit when he never did use nuclear weapons, despite getting bogged down in the Ukraine War.Story continues below this adKim Jong Un probably developed the strongest reputation for madness of any of the leaders you mentioned. With extreme threats and surprising actions, such as executing his own uncle and brother in dramatic ways, he came to be seen as both extreme and unpredictable. He is probably the closest analogy for Trump.In the past, the “madman theory” was often seen as effective owing to information being scarce or tightly controlled. In this age, when every action and statement is decoded and dissected, what are the limits to this approach?One limitation of the madman theory relates to the difficulty in establishing a reputation for madness. It is necessary to consistently project an image of madness. Even Nixon struggled with this, but a larger number of information sources exacerbate this challenge.Another challenge is that even though perceived madness can boost the credibility of threats, it can also undermine the credibility of commitments to peace. Not trusting a perceived madman’s commitment to peace can lead an adversary to resist his demands, believing conflict is inevitable regardless. This may partially explain why Iran dragged its feet on negotiating with the US.Story continues below this adWhat impact has Trump’s approach had in terms of how current and future US foreign policy will be perceived — both internally and externally?Madman theory is intended to be a crisis bargaining strategy, and it may have some benefits in crises — although the downside I mentioned above is important.Outside of crises, however, having a leader who is perceived as a madman will cause the United States to be perceived as a less reliable partner for cooperation. It also reduces the US’s image of responsibility and competence. Thus, I ultimately expect it to decrease the US’s standing in the global order.