Foreign policy doctrines are often forgotten as soon as they are written. Take the November 2025 US National Security Strategy, which told us that “the days in which the Middle East dominated American foreign policy … are thankfully over”. Keir Starmer, however, has stuck to his promise to “use realist means to pursue progressive ends”, even when placed in a difficult position by Donald Trump. The prime minister’s decision not to take part in offensive military action in the Middle East is, I would argue, consistent with his foreign policy doctrine of progressive realism. There is, of course, room for debate. Some progressives will point to the Iranian government’s egregious human rights abuses as reason for supporting externally enforced regime change. UK government ministers acknowledge this – they are not mourning the Ayatollah.But progressivism is also committed to peace between nations. This is because nationalism, as well as a yearning for individual freedom, is a powerful ideology. Foreign intervention can often provoke a nationalist backlash, even if its aims are to advance universal rights. While many Iranians celebrate the death of the Ayatollah, they may be wary of supporting external intervention.This is the progressive value of an international law that rejects the great power’s right to overthrow other governments. It defends the right of national self-determination, and believes human rights are ultimately more secure when nations live together peacefully. If nations are less suspicious of each other, they are less inclined to crackdown on domestic opposition. That creates the political space – so the theory goes – for gradual, less violent reform.Labour prime ministers have not always understood progressive foreign policy in these terms. Tony Blair took a more revolutionary approach. His decision to join the Bush administration’s 2003 war to overthrow the Iraqi regime was motivated in part by the progressive’s commitment to improve the lives of those repressed by dictatorships. His case for war centred on the threat of weapons of mass destruction, but his decision to join the US aligned with an American neoconservative view of promoting democracy through regime change. That ended badly, with tens of thousands of civilians killed in the violence that followed.These “mistakes of the past” were uppermost in Starmer’s thinking when he addressed parliament on March 2. The possibility that the unintended consequence of military action could be deadly chaos, rather than democratic revolution, reflects the realist side of UK foreign policy.Foreign policy realists have less faith in the progressive value of international law. Yet they are often aligned with progressives in opposition to military-enforced regime change. Realists appreciate that the mobilising force of nationalism makes the foreign intervener’s task much more difficult. A realist ethic focused on a prudent assessment of consequences makes them sceptical toward revolutionary goals and military gambles.Again, there is room for debate. The current US National Defense Strategy has a different understanding of realism. It throws out utopian idealism and brings in hard-nosed realism. This perspective demands the pursuit of ever more military power to secure the state in a position of undisputed primacy. Consequences still matter when considering when to use force, but priority is given to demonstrating a status of military superiority and political dominance.This kind of realism is, of course, unavailable to all but a few superpowers. The fact that it has been adopted by the UK’s one-time closest ally is troubling. US power used to be restrained by a combination of classical realist prudence on the one hand, and a liberal internationalism committed to multilateral decision-making on the other. Trumpian realism, however, seemingly rejects this in favour of demonstrating the president’s power to decide at will which foreign regimes should survive. So long as the UK remains committed to progressive realism, the Trumpian realist pursuit of regime change in states like Venezuela and Iran will put even more pressure on the special relationship. Read more: Iran is putting pressure on the US-UK ‘special relationship’ – but it has survived worse A more authentic realismNot all foreign policy experts are happy with how the US is now invoking realism. Kevin Maloney of the Carnegie Council, a thinktank dedicated to ethics in international affairs, accuses the Trump administration of “gaslighting” when it describes its foreign policy as “realist”. He points to a more authentic form of realism in the ideas of intellectual giants like German-American political scientist Hans Morgenthau. Morgenthau warned against both ends of the progressive realist spectrum: power detached from progressive values can be just as dangerous as ideals detached from power.The fusion of progressivism and realism in UK foreign policy led on this occasion to a “deliberate” decision not to support US military action against Iran. That annoyed Trump, but as Maloney’s assessment illustrates, it is not necessarily out of step with a wider tradition of American foreign policy thinking.One thing that progressives and realists agree on is that the state has a responsibility to protect its own citizens, including those abroad. Starmer’s eventual decision to allow the US to use UK bases for this defensive purpose was, arguably, consistent with his initial policy, and not another U-turn.Of course, doubts remain that the US will use UK assets for defensive purposes alone. But the decision is understandable in the context of Iran’s widespread retaliation and the risk it poses to the 300,000 UK citizens in the region. One possible scenario is that the UK may need to call on US capabilities to evacuate those citizens, as well as prevent Iranian missile strikes. Maintaining access to those capabilities is a prudent move in line with the national interest. In the longer term, the UK and other “middle powers” need to develop their own capabilities so that they are less dependent on the US, and more able to maintain their progressive realist stance.Jason Ralph has previously received funding from Research Councils UK and the European Union. He is a member of the UK Labour Party.