Gwynne Dyer is a Canadian-born independent journalist whose column is published in more than 175 papers in 45 countries.

Would Vladimir Putin’s Russia have invaded Ukraine three weeks ago if it had 1,900 nuclear warheads on 176 ICBMs and 2,600 tactical nuclear weapons? Of course not. He wouldn’t have invaded if Ukraine had even one nuclear missile capable of reaching Moscow.

When the Soviet Union was dissolved in 1991, Ukraine got custody of all those nuclear weapons because they had been based on its territory at the time of the break-up. Suddenly, Ukraine was the world’s third biggest nuclear power, with more warheads than Britain, France and China combined.

The Russians and the Americans were very unhappy about Ukraine’s nukes in the early 1990s, so they used political pressure and judicious bribes to persuade the new Ukrainian government to hand them all over to Russia for destruction. It got firm security guarantees from them in return, so it didn’t seem to be a foolish decision at the time.

The US now says that it can’t intervene to defend Ukraine because that might cause a nuclear war with Russia. So much for the arguments against nuclear proliferation. NOT proliferating can get you killed – as a couple of other leaders have already learned.

Saddam Hussein, the Iraqi dictator, had a nuclear weapons programme during his war with Iran in the 1980s, but it was comprehensively dismantled by UN inspectors after he invaded Kuwait and was defeated in the first Gulf war in 1990-91.

He never restarted that nuclear weapons programme, but the United States invaded Iraq anyway in 2003 and the puppet government it installed in Baghdad hanged him. The take-away was: for a dictator, nuclear weapons are the only life insurance that really works. North Korea tested its first nuclear weapon in 2006.

The Libyan dictator, Muammar Gaddafi, was so frightened by the American display of lawlessness in the 2003 invasion of Iraq that he let himself be bullied into closing down his own decade-old nuclear weapons programme. Big mistake.

Eight years later, in 2011, Gaddafi himself was driven from power by NATO air strikes, and then murdered by NATO-backed rebels. His own fault: he had jumped the wrong way. But once again, it was a cruel dictator who paid the price, so who cares?

In 1994, Ukraine let itself be sweet-talked into giving up all its nuclear weapons. A week ago, Sky News asked Svitlana Zalishchuk, foreign policy adviser to the Ukrainian deputy prime minister, if that had been a mistake.

“Yes, without a doubt,” she replied. Countries that own nuclear weapons are “untouchable”, and it is “because we voluntarily gave up on our nuclear weapons (that) we find ourselves in the situation that we are in.”

It turns out that not only evil dictators need nuclear weapons. Any country that has a nuclear-armed neighbour with a grievance urgently needs them too. Indeed, any country that thinks it might one day find itself in a confrontation with a nuclear-armed country, however far away it may be, needs nuclear weapons.

If you doubt me, just ask Finland and Sweden, neutral countries that are now thinking of joining NATO. Ask the Iranians or the Taiwanese, who are both rethinking their options. Or even ask the South Koreans, the Japanese and the Vietnamese, come to that.

If you get into a confrontation with a nuclear power, and you don’t belong to a nuclear-armed alliance like NATO, then you cannot trust any other country to risk a nuclear war on your behalf. ‘Guarantees’ and ‘assurances’ are useless. You need to have your own nukes.