Anton Chekhov’s rule was that if a gun appears in act one, by act three it must go off. This basic principle of drama holds true in diplomacy as well: don’t make promises you can’t keep, or threats you can’t deliver on. It’s a principle that Conservative politicians blathering about conflict with Spain over Gibraltar would do well to study.

On Sunday, the former Tory leader Michael Howard, citing Margaret Thatcher’s war with Argentina over the Falkland Islands, said he was “absolutely certain that our current prime minister will show the same resolve in standing by the people of Gibraltar”. It was no slip. This war meme over Gibraltar is not new in Tory thinking. Luke Coffey of the Heritage Foundation – a US conservative thinktank – has, since the Brexit vote, been calling for warships to be deployed around Gibraltar. Yesterday, in response to the row over Howard’s comments, Coffey retweeted a picture of the Argentine cruiser General Belgrano sinking.

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Sending warships to Gibraltar, and preparing what Coffey calls a “robust air bridge” should Spain close the land border, makes sense only if you buy the wider fantasy: that Britain’s future after Brexit involves rekindling its colonial empire, both as a market and a diplomatic sphere of influence.

The economist Andrew Lilico, a hard Brexiter, advocates the creation of an alliance called Canzuk – involving Britain, Canada, Australia and New Zealand together with former colonial dependencies. Although Britain’s trade with the Canzuk countries amounts to just 3% of GDP (compared with 40% with the EU), for Lilico it’s not just about trade. He wants a military alliance involving the primarily white, English-speaking countries, backed up with a new free-movement deal.

Lilico’s rationale rests on the “cultural similarity” of the Canzuk countries, which he assumes could override, say, the geographic proximity of Australia to China, and Canada to the US. Bonkers though it sounds, the proposal is more realistic than the official policy of the British government, which its own civil servants have derided as “Empire 2.0”.

Liam Fox, the minister for international trade, last month began the process of persuading the 52 nations of the Commonwealth – including giant populations in India and Nigeria – into a free-trade agreement with the UK. The only problem is, as 32 of them pointed out, they already have free trade with the EU via special agreements with the UK. If the UK leaves the EU before signing free-trade agreements with these ex-colonies, trade will be more free between them and the EU than it will be with the UK.

Empire 2.0 is, then, in all its forms, a fantasy. It is a displacement activity for Fox and his cronies in the rightwing thinktanks to avoid confronting the main task posed by Brexit: to salvage our trading, diplomatic, military and cultural ties with Europe.

But it has deep roots not just in the thinking of the Tory right, but in that of a xenophobic minority in England whose consciousness is moulded by the Daily Mail, nostalgia dramas on TV and an almost continuous stream of military pageants on this or that anniversary of this or that war.

For them, the UK’s connections with Europe were always the source of cognitive dissonance. Britain’s essential destiny was to “rule the waves”, not just through sea power, but through the cultural hegemony of its pop icons and its fashion designers.

That was always the subtextual meaning of the small wars the UK kept fighting: over the Falklands, with Iceland over fishing rights. It was the subtext, too, for the weirdly distributed bases of the British army: jungle training in Belize; the Gurkhas, stationed not just in Nepal but in Brunei; the two sovereign territories on Cyprus; and, of course, Gibraltar itself.

Maintaining a string of non-defensible bases between Borneo and Bermuda made sense as long as these were merely the legacy of an empire. But after 2010, Conservative military-diplomatic policy, under the influence of Coffey, among others, evolved towards the totally unrealistic philosophy of “global reach”.

Enshrined in the 2015 Strategic Defence and Security Review, global reach revived the principles of imperialist thinking. The UK’s military-diplomatic strategy is designed to enhance its “security and prosperity”. Although it sounds meaningless, this phrase has for the Tories a specific meaning: we will go on arming dictators as long as they are not a threat to the UK; we will sign lucrative training deals with the armies, dictators and autocrats as long as it promotes trade. And we will project power way beyond the Nato eastern flank and the Middle East, the two regions where UK military power has been focused for decades.

Even in 2015 this was laid out as a clear alternative to the most logical policy: of military co-operation with our European neighbours. The problem is, the rules-based multilateral system is fragmenting and the UK is faced with serious choices.

To the east is Vladimir Putin’s Russia, heavily re-armed, its submarines closely trailing every Trident-armed submarine that leaves Faslane, its cyber-warfare systems constantly probing ours. Between us and Russia is a continent riven with divisions and lacking resolve even to formally meet its Nato commitments.

All around us is the global threat of jihadism, together with the possibility of country breakdown and mass population movements.

These two threats – Russia and jihadism – are more than enough. We should design our military and diplomatic strategy to meet them and nothing else. Global reach is a post-imperial fantasy, as is the plan for Canzuk. So is the proposal to face down Spain diplomatically and insist on the absolute sovereignty of Gibraltar.

Gibraltar’s sovereignty was shared with Spain’s the moment EU membership for both territories led to their economic re-integration.

A rightwing nationalist government in Madrid was always going to play games like this if you handed them negotiating power by threatening a hard Brexit. In that sense, the Gibraltar row has emerged from Brussels as a credible threat from the EU to counter the credible threat of a no-deal Brexit.

But the UK’s security relies on Europe’s security. In reality, our trade and cultural links are primarily European and will go on being so. Let’s leave imperial fantasies to the weird Nietzscheans of the Tory right, who believe in triumph of the will over the objective realities of multilateral global power. Let’s say this to our Spanish friends: 70 years ago, 500 British and Irish men died trying to save democracy in Spain. For their memory, and for peace in Europe, we will never threaten a democratic and peaceful Spain with military force.