Ukraine's President Volodymyr Zelensky continues to send out a firm message of defiance.

When we met this weekend in the government headquarters in Kyiv, he said that far from losing, Ukraine would end the war victorious. He was firmly against paying the price for a ceasefire deal demanded by President Vladimir Putin, which is withdrawing from strategic ground that Russia has failed to capture despite sacrificing tens of thousands of soldiers.

Putin, Zelensky told me, has already started World War Three, and the only answer was intense military and economic pressure to force him to step back.

"I believe that Putin has already started it. The question is how much territory he will be able to seize and how to stop him... Russia wants to impose on the world a different way of life and change the lives people have chosen for themselves."

What about Russia's demand for Ukraine to hand over the 20% of the eastern region of Donetsk that it still holds - a line of towns Ukraine calls "fortress cities" - as well as more land in the southern regions of Kherson and Zaporizhzhia? Isn't that, I asked, a reasonable request if it produces a ceasefire?

"I see this differently. I don't look at it simply as land. I see it as abandonment - weakening our positions, abandoning hundreds of thousands of our people who live there. That is how I see it. And I am sure that this 'withdrawal' would divide our society."

But isn't it a good price to pay if that satisfies Putin? Do you think it would satisfy him?

"It would probably satisfy him for a while... he needs a pause... but once he recovers, our European partners say it could take three to five years. In my opinion, he could recover in no more than a couple of years. Where would he go next? We do not know, but that he would want to continue [the war] is a fact."

I met Zelensky in a conference room inside the heavily guarded government enclave in a well-to-do corner of central Kyiv. In the interview he spoke mostly in Ukrainian.

You get a sense of the weight of leadership carried by Zelensky from the diligence of his security guards.

Visiting any head of state requires rigorous checks. But entering the presidential buildings in Kyiv takes the process to a level I have rarely experienced before.

It is not surprising in a country at war, with a president who has already been targeted by Russia.

Despite all that, the man who started as an entertainer, who won the Ukrainian version of Strictly Come Dancing in 2006, and played the role of an unexpected president of Ukraine in a TV comedy, before becoming the real-life president of Ukraine, seems to be remarkably resilient.

US President Donald Trump said on the eve of the most recent ceasefire talks in Geneva that "Ukraine better come to the table fast".

He continues to default to putting more pressure on Ukraine than on Russia.

Western diplomats have indicated since last summer that Trump agrees with Putin that territorial concessions from Ukraine to Russia are the key to the ceasefire Trump wants, ideally before this coming summer.

Plenty of analysts outside the White House also judge that Ukraine cannot win the war and, without making concessions to Moscow, will lose it.

I asked Zelensky whether Trump and the others had a point.

"Where are you now?" Zelensky asked in return. "Today you are in Kyiv, you are in the capital of our homeland, you are in Ukraine. I am very grateful for this. Will we lose? Of course not, because we are fighting for Ukraine's independence."

Zelensky has often said that Ukraine can win, but what would victory look like?

Of course, he said, victory meant restoring normal lives for Ukrainians and ending the killing. But the wider view of victory he presented was all about a global threat that he says comes from Putin.

"I believe that stopping Putin today and preventing him from occupying Ukraine is a victory for the whole world. Because Putin will not stop at Ukraine."

You are not saying that victory is getting all the land back, are you?

"We'll do it. That is absolutely clear. It is only a matter of time. To do it today would mean losing a huge number of people - millions of people - because the [Russian] army is large, and we understand the cost of such steps. You would not have enough people, you would be losing them. And what is land without people? Honestly, nothing."

"And we also don't have enough weapons. That depends not just on us, but on our partners. So as of now that's not possible but returning to the just borders of 1991 [the year Ukraine declared its independence, precipitating the final collapse of the Soviet Union] without a doubt, is not only a victory, it's justice. Ukraine's victory is the preservation of our independence, and a victory of justice for the whole world is the return of all our lands."

A year ago, Zelensky visited the White House and received a reception one senior Western diplomat described to me as a pre-planned public "diplomatic mugging" from Donald Trump and his Vice-President JD Vance.

Their argument, in the presence of the world's media, was watched by millions around the world.

Trump, just inaugurated as president for the second time, was sending the strongest possible signal that the era of support Zelensky and Ukraine had relied on from President Joe Biden was over. Nato members were already on notice from the new administration. Vance had just got back from shattering Western European illusions about the strength of the trans-Atlantic alliance.

Since then, reportedly coached by Britain's National Security Adviser Jonathan Powell among others, Zelensky has avoided public confrontations with Trump.

The US president has stopped almost all shipments of military aid to Ukraine. But the US still provides vital intelligence, and European countries are spending billions buying weapons from the Americans to give to Ukraine.

I asked Ukraine's president about Trump's often contradictory statements, recalling that among the untruths he has uttered is the accusation that Zelensky is a dictator who started the war - a precise echo of claims made by Vladimir Putin.

Zelensky laughed.

"I am not a dictator, and I didn't start the war, that's it."

But can you trust Trump? If you extract a security guarantee from him, I asked, would he keep his word? He is after all a man who changes his mind.

"It is not only President Trump, we're talking about America. We are all presidents for the appropriate terms. We want guarantees for 30 years for example. Political elites will change, leaders will change."

He meant that US security guarantees needed approval from Congress in Washington DC to make them watertight.

"They will be voted on in Congress for a reason. It's not just presidents. Congress is needed. Because the presidents change, but institutions stay."

In other words, Donald Trump might be unreliable, but he will not be there for ever.

Zelensky says those security guarantees would have to be in place before he could consider another US demand - for Ukraine to hold a general election by the summer, echoing another Russian talking point that Zelensky is an illegitimate president. Trump has not demanded elections in Russia, where Putin became leader for the first time on the last day of the 20th Century.

Zelensky said he had not decided whether to stand again, whenever an election is held: "I might run and might not."

Elections were due in 2024, but they could not be held under martial law that was introduced after Russia's full-scale invasion.

Holding postponed elections, Zelensky said, was technically possible if they had time to change the law to allow them to happen. But he needed security guarantees for Ukraine first.

He went on to raise so many potential problems about holding an election with millions of Ukrainians abroad as refugees and significant tracts of the country occupied by Russia that I suggested that in reality he was against the idea.

"If this is a condition for ending the war, let's do it. I said, 'honestly, you constantly raise the issue of elections'. I told the partners, 'you need to decide one thing: you want to get rid of me or you want to hold elections? If you want to hold elections, (even if you are not ready to tell me honestly even now), then hold these elections honestly. Hold them in a way that the Ukrainian people will recognise, first of all. And you yourself must recognise that these are legitimate elections'."