The morale among my Ukrainian friends yesterday morning was certainly buoyant – the most hopeful I’ve heard from them in a long time.

The series of Trump-Zelensky-Europe meetings in Washington were not just good, they said. They were the best, the best so far.

After witnessing Putin receive a warm welcome in Alaska, they now feel they are close to obtaining an invaluable prize, something that Donald Trump has proposed, which none of his predecessors dared to offer.

We are referring to security guarantees – a pact where, should Ukraine face an attack, all the treaty’s signatories would promptly come to its defense (a promise Ukraine would naturally reciprocate).

It is hard to overstate the importance, or potential importance, of what Trump is now saying.

The whole problem with post-cold-war Ukraine is that it has been lost in geo-strategic ambiguity.

Are Ukrainians truly in a free, sovereign, and independent nation, as declared by the 1991 constitution? Ukrainians might overwhelmingly think they’re free – but do we?

Do we mean it when we say that Ukraine is independent?

Or do we, in the West, silently believe that Ukrainians are still somehow under Moscow’s influence, part of an unspoken Russian ‘sphere of influence’; essentially, a satellite, a vassal of the Kremlin, unable to genuinely determine their own fate?

For over 30 years, we’ve sent conflicting messages. We’ve expressed anger at Russia’s actions toward Ukraine, yet we’ve never done nearly enough to prevent such aggression.

We have failed for decades to offer the Ukrainians the protections we offer the Baltic States and all the other Eastern European countries. We have failed, despite repeated paper promises, to give them Nato membership.

This wasn’t because of some secret undertaking made to Gorbachev during the negotiations on German unification (that’s all Kremlin lies), and it wasn’t because America was in principle opposed. A glance at history shows that George W Bush accurately foresaw the threat of Russian attack, and actually campaigned for Ukraine to join the alliance.

No, the problem was that the Europeans, led by Germany, were too addicted to Putin’s oil and gas, and bowed to Russian pressure. It was the Europeans who always vetoed Ukrainian membership of Nato, and it was European weakness that helped to trigger the disaster.

Putin looked at that failure to offer Nato membership and drew the logical conclusion: that the West was not serious in its commitment to Ukraine’s borders or independence. That’s why he invaded the Crimean Peninsula in 2014, and when the West did little or nothing in response he decided to invade again in 2022.

That’s why the solution now – the only way to avoid a third invasion, and to achieve a lasting peace, is to provide security guarantees on the lines of Nato’s Article 5, a guarantee provided by countries comprising the vast bulk of Nato’s military power, and others beyond, such as Australia.

As Trump rightly says, the Europeans would lead but America would have a ‘coordinating’ role.

That is crucial, because any such effort would continue to depend on US logistics and intelligence. I have no doubt that the US would do much more besides. Trump himself has repeatedly declined to rule out US boots on the ground.

From the text of the Minerals Agreement to Trump’s latest commitments, we are seeing a growing Western commitment to Ukrainian security, guaranteed not just by the Europeans but also by the greatest military power on earth.

That is also a huge achievement by Volodomyr Zelensky. He is moving his country out of the grey zone, and into the column of Western-facing democracies – like South Korea, Japan, Israel – whose freedom is backed up by America.

It will mean – if we get such a peace agreement – that Ukraine can immediately press on with EU membership, and as Ukrainian society adopts Western norms the place will become less corrupt and more attractive to investment. It is a fantastic prospect if we get such a deal.

It is, of course, a very big if.

Despite their sudden surge of optimism, the Ukrainians know that there is no point in having security guarantees, when there is still no peace to guarantee. Putin may indeed want peace, as Trump says, but he wants peace only on his terms – and his current terms are outlandish.

He now says that he wants the whole of the Donbas; that is, to use the negotiations to gobble up heavily defended territory his forces have failed to capture for the last 12 years. There is a good reason why the Russians have failed, and why the Ukrainians have fought like lions to hold them off.

These are the very positions the Ukrainian forces need to hold, if they are to stop a Russian breakthrough across the flat and less defensible territory that leads to Kyiv and Kharkiv. In other words, Putin wants the Ukrainians to sign their own strategic death warrant.

It’s all very well having the prospect of Western security guarantees, but as every European leader was at pains to point out in the meeting on Monday, the best guarantors of Ukraine’s security are, and will always be, the heroes of the Ukrainian armed forces. They need those fortifications in the Donbas. They need that territory.

Even if Zelensky wanted to capitulate to this crazy demand of Putin’s, and to hand over a huge chunk of sovereign Ukrainian land, he would first have to change the Ukrainian Constitution. More importantly, he would have to deal with the outrage done to Ukrainian national feeling.

The Ukrainians have spent more than ten years fighting in defence of this land. They have lost tens if not hundreds of thousands of lives. They will not allow it just to be handed to Putin, by Zelensky or any other leader.

Putin knows it is not a runner, and that of course is why he is asking for it. We will see what happens in the next few meetings, but I am afraid that the Russian leader will now try to turn it round and blame Zelensky for being unreasonable. Putin cannot be allowed to get away with it.

Putin will torture Ukraine until he is forced to desist; as US Senator Lindsey Graham correctly says, he will keep going until he faces real economic ruin. To get a result – and end this war – we will all have to put more pressure on Putin.

That means continued and intensified military support for Ukraine. It means cracking down on Putin’s ‘shadow fleet’ being used to smuggle out his oil, secondary sanctions on his customers, and seizing the $300bn of his frozen assets.

Unless we act fast, and hit Putin where it hurts, I am afraid Russia will continue cynically to spin it out.

Trump has at least brought Putin to the table and broken the logjam. By offering Ukraine real security guarantees he is finally answering the crucial question – about the destiny of Ukraine.

It is only when Putin finally understands that Ukraine is now a long-term ally of America, and will be strongly defended by America, that he will understand that he has no choice but to let Ukraine go. That is the way to long-term peace.