THE only country ever to adopt a policy of unilateral nuclear disarmament is the Ukraine: in 1994, by signing the Budapest Memorandum on Security Assurances, it gave up what was the world’s third largest stockpile of nuclear weapons in return for a guarantee of its territorial integrity.

The co-signatories were the Russian Federation, the USA and the UK.

Twenty years later the Ukraine has seen its territory violated and annexed by one of the co-signatories to that agreement.

Apologists for the abrogation of the Budapest Memorandum by the seizure of the Crimea from the Ukraine, such as Nigel Farage of UKIP, have blamed the EU’s territorial ambition for having provoked Russian aggression.

I am not, and never have been, a fan of the EU but to blame it for Russia’s abrogation of the Budapest Memorandum is quite extraordinary.

It is an absurd proposition to assert that our willingness to open our markets to trade with nations which border our joint customs union can be an excuse for armed intervention by a third party.

Those making excuses should think back to Putin’s Soviet predecessors and remember that they called those bourgeois apologists for their crimes “useful idiots”, and reflect.

What is chilling about the events of the last few weeks is the reversion of Russia to its former Soviet stereotype and its adherence to the principle that the bigger the lie, the more believable it is.

When Russian special forces parachuted into the Crimea we were assured they were nothing to do with Russia, that it had no troops there, that they were local militias, and that Russia had no control over them.

Perhaps the greatest achievement of the latter part of the 20th century, was the dissolution of the USSR and the liberation of its client states, symbolised so dramatically by the tearing down of the Berlin Wall.

But for Mr Putin, a former KGB officer, it was a disaster.

That artificial construct, which President Reagan rightly called the “evil Empire” was sealed off behind what Churchill dubbed the Iron Curtain.

It was a place where crimes as great, if not greater, than Hitler’s were committed, a system that used ethnic cleansing and starvation as instruments of policy, imprisoned its dissidents in psychiatric hospitals or gulags and ruthlessly crushed the attempts of Hungary and Czechoslovakia to loosen the shackles.

It was a system from which Russia itself escaped, but under Putin it now appears to be displaying worrying signs of reverting to type.

A number of constituents have written to me to say that this isn’t our fight and what, after all, is the difference between a referendum in the Crimea and a referendum in Scotland? There is a world of difference.

The UN charter principle of self-determination ought properly to apply to both. I do not believe that the Ukraine could, or should, hold on to the Crimea if a majority of its people want to be part of Russia, any more that I believe that that the UK could hold on to Scotland if the Scots vote for independence in September this year.

The difference is that Scotland’s referendum is lawful.

Our response should be economic, and it should be diplomatic. Everyone seems to agree that it mustn’t be a military response. I disagree: as the Roman said “Si vis pacem, para bellum” – if you wish for peace, prepare for war.

The proper response is to do exactly what we are already doing: to rearm.

We are committed to spending £160bn in equipment over the next decade.

The problem is that we are virtually alone in NATO in meeting the target of spending two per cent of our GDP on defence.

It is our allies that need to raise their game.