‘Madman Theory’: President Trump’s Volatility & Implications for Policymakers
Tom Hayward | 21 July 2025
Summary
United States (US) President Trump has deployed unpredictability as a strategy reminiscent of former President Richard Nixon’s “madman theory” tactics: using erratic rhetoric and actions to gain a strategic advantage.
The strategy has yielded short-term gains, but risks undermining long-term US credibility and alliance cohesion.
Such US unpredictability creates uncertainty for policymakers across diplomatic, security and economic domains.
In his second presidential term, President Trump has used unpredictability as a tool of diplomacy, echoing President Nixon’s employment of the “madman theory”. The strategy is used by leaders who seek to create an impression of unpredictability. It can be used to convince allies and adversaries alike that all options, even those that seem unthinkable, are on the table.
Prominent manifestations include threats to annex Greenland and suggestions that Canada should become the 51st US state, with such statements consequently projecting an image of a leader willing to pursue radical actions. President Trump’s strategy is also reliant on credibility ,as other parties must believe that belligerent rhetoric can translate into action. Consequently, ‘Liberation Day’ and the imposition of “reciprocal tariffs” on 57 countries deliberately set the tone for Trump’s presidency. This posture has been actualised through recent strikes on Iran’s nuclear facilities, strengthening the credibility of Trump’s belligerent rhetoric.
Trump's background in real estate and deal-making has informed his approach to international relations .Trump's second-term approach to Ukraine, where he reportedly told President Volodymyr Zelensky "you don't have the cards" before withdrawing military support, shows the unpredictability now extends beyond rhetoric to concrete policy actions.
The strategy extends into interpersonal dynamics, particularly evident in White House interactions. Trump’s tense exchanges, such as those with South African President Cyril Ramaphosa, are designed to put foreign leaders on the defensive and give Washington an upper hand in negotiations. Foreign leaders determined to avoid embarrassment are incentivised to offer concessions before they even arrive.
Trump has further utilised unpredictability as a strategic tool. In the recent Iran episode, he publicly called for a 2-week negotiation window, only to launch strikes on Iranian nuclear facilities just hours later. The sudden reversal caught both allies and adversaries off-guard. Such inconsistency undermines trust in negotiations, making other actors less likely to enter talks in good faith. Adversaries may interpret US diplomatic efforts as feints, while allies may become increasingly reluctant to rely on American assurances or intelligence assessments.
The approach has seen some initial success. With allies, it has shifted negotiation dynamics and encouraged some leaders to offer concessions. The North Atlantic Treaty Organisation’s (NATO) agreement to increase defence spending to 5% of GDP is indicative that Trump’s volatility can yield quick wins on the international stage. Yet the strategy has also encountered limitations. Russian President Putin has proved resistant to Trump’s volatility, in part because Trump has been reluctant to use threats or action to force the Kremlin’s hand. While Washington has paused arms deliveries to Ukraine, Trump only stated that he was “disappointed” that Putin was not ready to end the war and has not followed through on threats to increase sanctions on Russia.
International responses have varied significantly. NATO Secretary-General Mark Rutte and Saudi Crown Prince Mohammed bin Salman have adopted fawning approaches. British Prime Minister Keir Starmer and Australian Prime Minister Anthony Albanese have approached their preparations pragmatically, considering various scenarios. European Commission President Ursula von der Leyen and French President Emmanuel Macron have adopted more distant approaches and publicly questioned the US’s commitment to multilateralism.
The White House/Wikimedia
Forecast
Short-term (Now - 3 months)
It is likely that provocative unpredictability employed by the White House will continue to yield concessions from allies and partners seeking to avoid confrontation.
It is likely that the UK’s foreign policy will remain highly reactive, due to a continued prioritisation of proximity over autonomy. As a result, Downing Street may be caught off guard by unilateral US actions or policy changes.
Medium-term (3-12 months)
It is highly likely that Washington’s deliberate volatility will continue to erode the role of global institutions, such as the UN, and, in particular, agencies like the International Atomic Energy Agency (IAEA).
While continuing public diplomatic efforts, it is likely that allied hedging will intensify; countries such as France, Germany, and Canada may quietly diversify their diplomatic, economic, and security dependencies away from the US.
Long-term (>1 year)
There is a realistic possibility that, if Trump’s strategy of deliberate unpredictability persists, alliances such as NATO will fragment as states build parallel pacts to increase their autonomy.
It is likely that the US will face growing reputational costs as its credibility as a diplomatic broker and security guarantor is eroded.
