The line from Thucydides, “The strong do what they can and the weak suffer what they must”, is getting quite the airing of late. You are meant to nod gravely along to it, as though it expresses a bitter but universal truth about international relations.
Does it, though? The phrase implies that a country becomes more aggressive as it grows more powerful. Well, the US was never mightier than it was around the time of Trump’s birth in 1946, when it made half of the manufactured goods in the world and had a nuclear monopoly too. With all this power, the US didn’t “do what it could” to the weak. Instead, it set up the Marshall Plan and Nato, those masterpieces of enlightened self-interest. It rebuilt Japan and Germany as pacifist democracies. The belligerent turn in American behaviour has in fact come during its relative decline.
Leadership explains some of this, in that Harry Truman was “better” than Trump, but only some. The rest is structural. It is easier for a nation to be magnanimous from a great height. Paranoia and aggression set in when that position slips. As such, we should expect a volatile US until it gets used to the role of being a, not the, superpower. Britain and France got there in the end, despite having to fall much further.
No one ever quotes the other bit of the famous Dylan Thomas poem about decline. After nagging the reader to “rage against the dying of the light”, he concedes that giving up makes more sense: “wise men at their end know dark is right.”
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Always beware a declining superpower – https://t.co/4Xah6qhSiO via @FT
— Marshall Auerback (@Mauerback) January 21, 2026
Like a wounded tiger, always most dangerous in that state
