The great unbreakable rule is supposed to be that no country can change another nation’s borders or government by force. The end of the Hitler war put a stop to all that sort of thing, or so we are told. 

Much has been made of this since the latest Ukraine peace talks flopped on Wednesday.

As it happens, I agree – who doesn’t? – that nations should not gain territory or anything else by aggressive brutality. I am also against countries changing other people’s governments, or fomenting ‘people power’ or civil wars on their territories, or any of those hoary old tricks, which can be just as bad as an invasion in the long run.

But there is, in fact, no such rule, and it is time we recognised it.

This country and the US, for example, jointly invaded Iraq in 2003 to change its government. It was a nasty government, but lots of countries have those and we do not invade them. What we actually wanted to do was to reduce the power of next-door Iran, which was the opposite of what happened, but never mind.

Nobody in London or Washington has ever been punished or dragged off to the International Court in the Hague for this. We suffer no sanctions or boycotts.

Amazingly, when our politicians piously condemn similar actions by Russia, nobody (except me) laughs. For 2003 is now long ago, firmly locked away in the cupboard of the yesterdays. But it is in that cupboard that we can find so many other examples of the disagreeable truth.

A ballistic missile explodes over Kyiv yesterday after Russia's latest strike 

The biggest of all is the great Yalta appeasement, when the Western nations handed over much of Europe, bound and gagged, to Josef Stalin’s untender mercies. They were afraid to fight him instead.

Included in this package was the bodily shifting of the whole territory of Poland. To compensate it for losing so much of its land to Moscow, to its east, Poland was awarded a sizeable bite out of Germany, to its west. This arrangement, along with the Russian seizure of the German city of Konigsberg, now Kaliningrad, has survived the end of the Cold War.

Millions suffered terribly in this and other linked border changes, and multitudes died in vast, unspeakably cruel ethnic cleansing, which is almost entirely forgotten.

On the basis of this bloody, cynical horror rested the entire period of prosperous and peaceful Western European history, which lasted until very recently.

Well, that, too, is long ago and far away. So how about another event recent enough to have filled our TV screens in the 1990s, the Yugoslav wars?

It will probably be another 50 years before any kind of fair, calm history is written of this horrible brawl. It has, I suspect, more culprits and villains than we like to admit and pretty much no saviours or heroes. But at the end of it, several astounding things had happened.

An entire country, Yugoslavia, had ceased to exist. It was replaced by several small nations that were swiftly drawn into the orbit of Europe’s postmodern, polite but firm empire, the EU.

Nato had abandoned its famous defensive posture and had launched bombing raids on Yugoslavia and especially Serbia, which were not in response to any attack on its members. And a new country, Kosovo, had been carved violently out of Serbia, formerly the dominant nation in Yugoslavia.

Currently 108 out of 193 UN members have recognised Kosovo’s declaration of independence. But the country it has declared independence from, Serbia, has not done so and is not likely to. Only external force could have brought this about, even if it is hard to identify exactly who did what.

Another Nato country, Turkey, has a poor record on the invasion front. In 1974 it seized Northern Cyprus, eventually swallowing more than a third of that island country’s territory. Turkey’s army is still there, and is not likely to leave, ever. The grab is not officially recognised, but nothing serious has ever been done to reverse it – Turkey remains a key part of the Western alliance.

You could argue in both these cases that the locals, the Kosovar Albanians and the Turkish Cypriots, were grateful for the lawless interventions of outsiders. Both faced living under hostile governments, a horrible fate.

But the Russian majority inhabitants of Crimea, who in 1992 were prevented by Ukraine from holding a referendum on their future, are also grateful to Moscow for their rescue from Ukrainian rule. There’s no doubt that they would have voted to join Russia, if allowed.

Then there’s 1978, when Israel handed back the Sinai Peninsula, which it had captured from Egypt 11 years earlier.

This huge surrender of territory was thanks to the once-famous Camp David accords – the work of US President Jimmy Carter, who forged a deal between Israel and Egypt even though the two states were so mutually hostile that their leaders, Anwar Sadat of Egypt and Menachem Begin of Israel, could barely bring themselves to speak to each other.

There is little doubt that this major handover of strategically vital land was the delayed result of Egypt’s surprise attack on Israel in 1973. When the world approves of this sort of deal, it calls it ‘land for peace’. When it disapproves, it calls it ‘appeasement’. The two are the same.

But the closest to home of all these events is the hardest to see. Thanks to brilliant Blairite spin-doctoring then and since, much of Britain has yet to realise that the United Kingdom surrendered to the Provisional IRA at the fabled ‘Good Friday Agreement’ in Belfast in 1998.

The IRA was richly rewarded for three decades of murder, torture and kidnapping. If it lost, why do you think the long-ago acts of British soldiers in Northern Ireland are still being investigated, while Patrick Magee, the multiple murderer who tried to assassinate the British Cabinet in Brighton, is a free man?

Why did the terrorist godfather Martin McGuinness find himself dining with the late Queen at Windsor Castle, wearing white tie and tails instead of his IRA balaclava? Is this what happens to the defeated?

And before all that long a large chunk of our national territory will pass irrevocably under the rule of a foreign state, as the direct result of a violent attack on this country, and of our wish for that attack to stop.

The 1998 agreement is clear. All it will take is a referendum, and the six counties of Northern Ireland will become part of the Irish Republic. This is what our government signed, though Ukrainians might be struck by the way our cave-in followed strong pressure from the US, which abruptly dropped its supposed close ally.

The defeated must do as they are told. If only poor President Zelensky of Ukraine had spin doctors as good as Sir Anthony Blair’s propaganda team. He might then be able to persuade his battered people to pretend they had won. As it is, his chances of selling any sort of peace to his own nation are nil.

Perhaps we could at least help him by explaining he is not the first to give ‘land for peace’, and won’t be the last.