IN THE YEARS before he became the second most powerful political figure in Ukraine, Andriy Yermak produced films. One of his more successful, “The Fight Rules” (2017), tells the story of a Ukrainian street-fighter called Taras. At one point, the hero declares he is governed by a single rule in life: “Finish him off before he finishes you off.” In a rare interview, President Volodymyr Zelensky’s chief of staff says that not even his scriptwriters could have imagined the horrors of Ukraine’s war. But his message differs little from that of his cinematic hero. “Ukraine needs to stand and survive,” he says. “If it doesn't, Putin will never stop.” The statement by Russia on March 29th that it will “drastically reduce” its attacks on Kyiv, which came after the interview took place, would, if true, certainly show the benefits of standing up to aggression, even if Vladimir Putin is far from finished off.

Mr Yermak is a complicated and secretive figure. Unlike his boss, he does not court media attention. His main currency is his closeness to the president, forged over a decade of friendship. Before the war began, the two used to arrive for work together. Since February 24th they have been sleeping in the same underground bunker. “We’ve not been home since then,” he says. Mr Zelensky certainly appears to trust his friend. He has delegated to him the most difficult tasks of his presidency, from handling Donald Trump during the Ukrainegate scandal of 2019 to directing the current peace negotiations with Russia. In the corridors of power, he is often referred to as the “vice-president” which, according to the Ukrainian constitution is a position that does not in fact exist.

Speaking at the presidential compound in central Kyiv, Mr Yermak lays out an optimistic vision of how the war is changing the world order and how Ukraine fits into it. “We have shown that it’s possible not to be afraid, not to have thousands of tanks or millions of troops. It is simply enough to be a brave and honest person that loves his country,” he declares.

The war, now in its fifth week, has clearly altered Ukraine’s view of itself. During its 30 years of independence, it felt like something of a poor relation to western Europe, tapping on the door for attention. Even organising a phone call to a foreign leader was a problem. “The attitude was more or less, ‘Yes, we know you exist, but we’ll give you a call later.’”

Five weeks of unexpectedly fierce resistance has changed all that. Mr Zelensky now fields up to a dozen high-level calls on a typical day. With the exception of the city of Mariupol, which appears to be entering the end game after a brutal siege that has left thousands dead, Russia is failing in its objectives. Mr Yermak insists that Ukraine is capable of counter-attacking and liberating its territories. “If we have enough intensive weapons, we will win,” he believes, though if the Russians dig in, evicting them will be much harder than stopping their advance. “I think there is one, or maybe two armies in the world that are capable of stopping the Russian army after a month of fighting. If I were a NATO member, I would be so interested in having a country that shows what it’s capable of in practice,” Mr Yermak insists—glossing over NATO’s main objection to Ukrainian membership, that it would risk a cataclysmic war with Russia.

Indeed, Mr Yermak goes even further, arguing that the international security system that has applied since the end of the second world war is over. In a new configuration, Ukraine, he argues, would hold a natural place as one of the “founders and leaders of that system”. If Western politicians fail to accept that, he says, their own voters may dismiss them. “The people in the streets of different countries around the world have already voted to support Ukraine. They have already voted to close the skies, they have already voted that Ukraine will be part of the European Union.” In getting what it needs, Mr Yermak says, Ukraine will not wait for politicians around the globe to grow more resolute. Instead, it will appeal directly to the people. “It’s time. If you are part of the wave, and feel it, you change. If you don’t, time changes you.”

Unfortunately for Mr Yermak, demonstrations are not in fact votes and they do not routinely change policy. Western politicians have resisted Ukraine’s demands for a no-fly zone, among other things, without suffering any discernible fall in popularity. Indeed, Emmanuel Macron, France’s president, has seen his chances of reelection surge as the war has ground on, despite being one of the more cautious voices in the debate about western intervention.

Yet Mr Yermak contends that Mr Zelensky has captured the world’s imagination, and especially that of young people. “I am not surprised because I know him. But I remember many opposition politicians making jokes about him not being a proper leader. I’d ask all of them to look me in the eye and say they’re ready to repeat their words.” In Mr Yermak’s view, Ukraine’s president will be able to persuade the world of his point of view. “Today,” he declares, “Zelensky is a leader of the free world.”