Ceasefires that are suddenly declared tend to be pretty fragile.

Stable ceasefires usually require a lot of preparation so that everyone on both sides knows what is supposed to happen, and – more importantly – when.

And they normally agree on how it will be monitored so one side cannot seize a quick advantage by breaking it suddenly.

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Without such preparations, and sometimes even with them, ceasefires will tend to be breached – perhaps by accident, perhaps because one side does not exercise full control over its own forces, perhaps as a result of false alarms, or even because a third party – a guerrilla group or a militia, say – choose that moment to launch an attack of their own.

The important question is whether a ceasefire breach is just random and unfortunate, or else deliberate and systemic – where someone is actively trying to break it.

Either way, ceasefires have to be politically reinforced all the time if they are to hold.

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All sides may need to rededicate themselves to it at regular intervals, mainly because, as genuine enemies, they won’t trust each other and will remain naturally suspicious at every twitch and utterance from the other side.

This is where an external power like the United States plays a critical part.

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If enemies like Israel and Iran naturally distrust each other and need little incentive to “hit back” in some way at every provocation, it will take US pressure to make them abide by a ceasefire that may be breaking down.

Appeals to good nature are hardly relevant in this respect. An external arbiter has to make the continuance of a ceasefire a matter of hard national interest to both sides.

And that often requires as much bullying as persuasion. It may be true that “blessed are the peacemakers”.

Volodymyr Zelenskyy has given a wide-ranging interview to Sky News in which he was asked about the prospect of Russia attacking NATO, whether he would cede land as part of a peace deal and how to force Vladimir Putin to the negotiating table.

The Ukrainian president spoke to chief presenter Mark Austin.

Here are the five key takeaways from their discussion.

NATO ‘at risk of attack’

Mr Zelenskyy said plans for NATO members to increase defence spending to 5% of GDP by 2035 are “very slow” and warned Russia could attack a NATO country within five years to test the alliance.

“We believe that, starting from 2030, Putin can have significantly greater capabilities,” he said. “Today, Ukraine is holding him up, he has no time to drill the army.”

But while Mr Zelenskyy conceded his ambition to join NATO “isn’t possible now”, he asserted long term “NATO needs Ukrainians”.

US support ‘may be reduced’

Asked about his views on the Israel-Iran conflict, and the impact of a wider Middle East war on Ukraine, Mr Zelenskyy accepted the “political focus is changing”.

“This means that aid from partners, above all from the United States, may be reduced,” he said.

“He [Putin] will increase strikes against us to use this opportunity, to use the fact that America’s focus is changing over to the Middle East.”

On the subject of Mr Putin’s close relationship with Iran, which has supplied Russia with attack drones, Mr Zelenskyy said: “The Russians will feel the advantage on the battlefield and it will be difficult for us.”

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Trump and Putin ‘will never be friends’

Mr Zelenskyy was sceptical about Mr Putin’s relationship with Donald Trump.

“I truly don’t know what relationship Trump has with Putin… but I am confident that President Trump understands that Ukrainians are allies to America, and the real existential enemy of America is Russia.

“They may be short-term partners, but they will never be friends.”

On his relationship with Mr Trump, Mr Zelenskyy was asked about whether he felt bullied by the US president during their spat in the Oval Office.

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“I believe I conducted myself honestly. I really wanted America to be a strong partner… and to be honest, I was counting on that,” he said.

In a sign of potential frustration, the Ukrainian president added: “Indeed, there were things that don’t bring us closer to ending the war. There were some media… standing around us… talking about some small things like my suit. It’s not the main thing.”

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Putin and peace talks

Mr Zelenskyy was clear he supported both a ceasefire and peace talks, adding that he would enter negotiations to understand “if real compromises are possible and if there is a real way to end the war”.

But he avoided directly saying whether he would be willing to surrender four annexed regions of Ukraine, as part of any peace deal.

“I don’t believe that he [Putin] is interested in these four regions. He wants to occupy Ukraine. Putin wants more,” he said.

“Putin is counting on a slow occupation of Ukraine, the reduction in European support and America standing back from this war completely… plus the removal of sanctions.

“But I think the strategy should be as follows: Pressure on Putin with political sanctions, with long-range weapons… to force him to the negotiating table.”

Russia ‘using UK tech for missiles’

On Monday, Mr Zelenskyy met Sir Keir Starmer and agreed to share battlefield technology, boosting Ukraine’s drone production, which Mr Zelenskyy described as a “strong step forward”.

But he also spoke about the failure to limit Russia’s access to crucial technology being used in military hardware.

He said “components for missiles and drones” from countries “including the UK” were being used by Russian companies who were not subject to sanctions.

“It is vitally important for us, and we’re handing these lists [of Russian companies] over to our partners and asking them to apply sanctions. Otherwise, the Russians will have missiles,” he added.

He’s an embattled wartime leader struggling to make himself heard.

For Ukrainian President Volodymyr Zelenskyy the war in Iran could not have come at a worse time.

Suddenly, the world’s attention is on a different conflict and – most crucially so – is the attention of the most powerful man in the world, Donald Trump.

Read the interview here

But this is a big 24 hours for Zelenskyy, a meeting with Sir Keir Starmer in Downing Street, followed by the NATO summit in The Hague.

When I sat down with Mr Zelenskyy in the last few hours, he had two main issues on his mind.

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Firstly, the proposed spending pledge by NATO countries of 5% of GDP by 2035 – that he said was too slow and warned that Putin would be ready with a new army within five years.

He said the Russian leader would likely attack a NATO country within a few years to test Article 5.

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Then he was on to sanctions, which, he told me, were not working.

Countries, including the UK, were allowing dual-use components used in the production of drones and missiles to still get into Russian hands, and that must be blocked.

He also still insisted there would be no negotiations without a ceasefire.

This war is not going well for Ukraine right now.

Nearly three-and-a-half years into it, the fighting goes on, and Mr Zelenskyy appears to be a defiant president determined to see it through.