While it is clearly too early to judge the long-term ramifications of the president’s decision to order the killing (my colleague Uri Friedman has set out the dangers of accidental escalation), the initial assessment among many in the foreign-policy establishment here in London is not quite what you might expect. The attack—in the view of analysts and British officials I spoke with (the latter of whom requested anonymity to discuss government discussions)—has, at a stroke, reasserted American military dominance and revealed the constraints of Iranian power.

Read: Iran’s response to Soleimani’s killing is coming

Although Trump’s foreign-policy strategy (if one even accepts that there is such a thing) has many limits, his unpredictability and, most crucially, his willingness to escalate a crisis using the United States’ military and economic strength have turned the tables on Iran in a way few thought possible. What is more, the strike has exposed the gaping irrelevance of Europe’s leading powers—Britain, France, and Germany—in this whole crisis. The “E3,” which have long sought to keep the Iranian nuclear deal alive by undermining the U.S. policy of “maximum pressure” on Iran, have so far failed to do so. This week, they were finally forced to admit the apparently terminal collapse of the Obama-era nuclear deal, releasing a joint statement to announce that they were triggering its “dispute resolution” clause because of Tehran’s failure to abide by the terms of the agreement. The reality of the situation is startling: Europe’s attempts to keep the deal alive have achieved little in Tehran because of the Continent’s powerlessness. And European opposition to Trump’s Iran policy has achieved even less in Washington. In an interview, Boris Johnson all but admitted defeat in keeping the nuclear deal alive, calling instead for a new “Trump deal.”

To some extent, one British diplomat told me, the air strike that killed Soleimani was an extreme snapback to the hyperrealist, Kissingerian principles that largely guided American foreign policy after the Second World War. In this view, Barack Obama and his cautious multilateralism were the break with the norm, not Trump.

While Obama showed the possibilities of this approach—the Paris climate accord and Iran nuclear deal being prime examples (both of which have since been dumped by Trump)—he failed to adequately address its weaknesses, those who spoke with me said. Principal among them, according to a British government official, was that under Obama, the West had forgotten the power of escalatory dominance. In other words, he who carries the biggest stick retains his dominance, so long as he is prepared to use it.

Read: The Obama Doctrine

The argument for escalation is simple: If the response to any aggressive act by a foreign adversary is always to de-escalate in order to avoid a spiral of violence, then the advantage borne by military and economic dominance is lost, creating more chaos, not less. A logic has been allowed to develop among countries such as Iran and Russia, the British diplomat said, that the West will not escalate a crisis and will remain boxed into its cautious, multilateralist view. Trump has changed this.