Just over two weeks ago, President Trump, bombed Iranian nuclear sites. Where does this leave the UK?

It is the first of June 2029 and China has just launched ballistic missiles aimed at Taiwan. Its aircraft carriers churn through the Ocean. US planes swoop down. War is declared.

Sir Keir Starmer sits in Downing Street and glances at his phone – BBC News updates him on the conflict as he is told by an automated voice that he is number 23 in the queue to speak to President JD Vance. With frustration rising, he is finally resigned to act. He hangs up, logs onto Twitter and, in language carefully honed over four years in government, declares the following:

“The United Kingdom condemns, in the strongest possible terms, China’s unprovoked aggression against Taiwan. This is a grave violation of international law and a serious threat to peace and stability in the Indo-Pacific. We stand in solidarity with our democratic partners and call on all parties to return to dialogue, de-escalate tensions and uphold the international rules-based order.”

For a moment, he simply leans back in his chair. The tweet was, by all accounts, exactly the sort of firm, principled response his aides had been workshopping for months. Carefully constructed. Dignified. Legally sound.

And entirely ignored.

Chinese boots touch down on Taiwanese beaches. Supply chains falter. Financial markets spasm. A Taiwanese official tells reporters, “We have no time for statements. We need action.”

Starmer watches in silence. He shakes his head and mutters under his breath: “Surely they understand this is a clear breach of international law.”

This is of course pure conjecture. But it serves as a fable to illustrate something real: the inefficacy of the UK’s approach towards foreign policy. The Iran crisis today highlights the ineffectiveness of clinging to a deceased liberal world order that only still exists in European capitals. The UK must abandon the illusion of leadership and accept a role grounded in hard-nosed alignment with its interests – not abstract ideals.

The Labour alternative is not much better. The Foreign Secretary David Lammy champions a doctrine he calls “progressive realism,” the use of realist tools to achieve progressive ends. Borrowing selectively from the ideas of liberal scholars like Joseph Nye, it attempts to reconcile hard power with moral purpose.

In theory, it is a mature reckoning with a changed world; in practice, it is a rebranding exercise. Rather than adapting to the rise of realism, Labour has simply redefined realism to fit its pre-existing values framework and nowhere is this contradiction more apparent, or more damaging, than in its approach to international law.

Labour has decided that upholding and strengthening international law is a ‘realist’ foreign policy as it theoretically will bind powerful states to agreed rules, reduce global instability and give the UK greater leverage in international affairs.

Attorney-General Lord Hermer declared in the aftermath of the strikes on Iran that the UK will “lead on international law issues,” but who is it leading? The American new right learned two key lessons from the failures of neoconservative interventionism in the early noughties: first, that the West has no moral authority to lead on anything; and second, that sovereign nations no longer wish to be led by outsiders. At the turn of the millennium, building foreign policy around international law might have been seen as idealistic – even bold. By 2025, calling it naïve is generous.

You cannot be a realist and an idealist. The international system is increasingly power-driven, capacity-based and multipolar. We may wish it were not so – we may wish relying on international law were an effective way to conduct foreign policy, but it is not. International law is as weak as it has ever been. Trump’s strikes on Iran are reportedly in breach of it, Russia’s invasion of Ukraine is certainly in breach yet enters its third year while Hungary has voted to withdraw from the International Criminal Court. To be a realist is to understand one’s own limitations. The UK should not be attempting to shape the international system; it should conform to it.

Despite everything, the UK remains well placed to maintain its relevance in a realist world order. It remains one of the world’s largest economies, a nuclear power and a founding member of NATO. It holds key military bases across Cyprus, Diego Garcia, Gibraltar, the Falklands and Bahrain. Even its permanent seat on the UN Security Council, although increasingly symbolic, still offers diplomatic leverage when coordinated effectively.

But relevance in a realist world is not just about possession of miliary assets – it is about the willingness to project and sustain power effectively. The UK must increase its defence spending if it intends to remain a credible actor in an increasingly militarised geopolitical landscape. This means investing in force readiness, hard power projection and cyber and space capabilities – not just symbolic deployments or diplomatic overtures. Rather than chasing moral leadership through legal norms, the UK should lean into what it actually is: a formerly great, upper-middle power that still has global reach and regional interests but also a shrinking margin for error. Relevance will not be earned by speaking the language of a world order that no longer exists but by adapting to the one that does.

On the Iran strikes, the UK was not consulted, not informed and its presence was not missed. It played no role, shaped no outcome and offered nothing that the key players needed or valued. This is the blunt reality of a state that continues to speak the language of norms in a world that now only listens to power. If the UK wishes to matter, it must stop appealing to systems that no longer function and start acting within the world as it is, not as it once hoped it might be.

Jake Weston is a Member of Bright Blue. The views expressed in this article do not necessarily reflect the views of Bright Blue.