One of the trademarks of Soviet generals was to order mass offensives by troops that did not exist. Famished and depleted brigades would be cajoled out of defensive positions, and made to run 50 yards into machine gun fire, in order to prevent their commander from getting court-martialed. The whole charade - beginning with the Spanish Civil War and reprised in 1941 - was, in its origin, political. Soviet communism had always to be seen as an attacking organism, never a defensive one.

As the May administration spirals towards its end, Defence Secretary Gavin Williamson is beginning to sound a lot like one of those Soviet generals. With a defence budget 18 per cent smaller than it was in 2010, he has claimed that Britain is to launch a string of bases that will, after Brexit, make it a “true global player”.

When a few refugees made it across the English Channel in ramshackle boats, evading the entire border security and naval apparatus of the “true global player”, the farcical nature of the claim was revealed. Britain does not even have the capability to police its own territorial waters. It is so far from being a “true global player” that – if we had a media capable of doing more than processing MoD press releases – Williamson’s claim would be laughed out of court.

But the philosophy of “global reach” has its roots in the same post-imperial fantasy as hard Brexit. Like the Soviet policy of attacking with non-existent troops, it is based on a political conceit dating back to the early 20th century: that Britain, with 0.87 per cent of the world’s population, can meet defensive commitments close to its borders while policing the rest of the world at will.

The modern policy of “global reach” was first outlined in David Cameron’s 2015 defence review: it committed the UK to a naval base in Bahrain, and envisaged a new expeditionary force of 50,000 personnel, capable of being deployed anywhere in the world.

Cameron and George Osborne linked this vision overtly to their strategy of building trade links beyond Europe. There was the same vague assumption that lay behind Hillary Clinton’s “pivot” to Asia: that the rules-based trading order would need to be underpinned by a Western military presence close to India and China.

In the end, the entire premise of the 2015 defence review has been exploded. The urgent threat remains jihadi terrorism. But the most important and strategic threat is Russia’s hybrid warfare operation against Western democracies. This could have been foreseen in 2015. But nobody foresaw that Putin would be gifted a plaything in the White House, dedicated to ripping up the multilateral, rules-based order and unleashing a trade war with China, while conducting unaccounted briefings with Putin himself and attacking the US’s own intelligence services.

Britain, sitting at the Western end of a continent riddled with social conflicts, which is being targeted by Putin’s hybrid warfare machine, needs a defence strategy and capability to meet this threat. Nothing in the 2015 document, and too little in Williamson’s cut-down review, entitled the Modernising Defence Programme and published last month, truly addresses this.

Instead, thanks to a combination of conservative cant, inter-service buffoonery and woeful illiteracy among MPs, we have the fantasy of “global reach”. All this with a navy comprised of just 19 big ships; an army which cannot fill its 8,200 manpower gap without employing migrants; barracks unfit to live in and a £15bn gap between procurement plans and the actual budget.

Right now, we have a battlegroup of 800 troops in Estonia, with tanks and armoured vehicles, plus another 130 operating under US command in Poland. But the real threat to our security is developing behind this frontline. It is developing in Budapest, where the Nato-member government is bought to the hilt by Russia. And in Austria, where the far-right/conservative coalition is pro-Putin. And in the far-right and right-wing populist movements across Europe, all of which are being manipulated by Russia, to fragment both NATO and the EU.

In his December statement, Williamson told MPs that “NATO is stronger and the UK is a leader”. Neither is true. NATO’s mutual defence commitment is becoming dangerously undeliverable. Vast swathes of civil society in Europe would not support any kind of military standoff with Russia, especially if preceded by a chaos-inducing hybrid warfare campaign, mobilising organised crime, propaganda outlets, high finance, corrupt politicians and the money of the American alt-right.

An added problem is the incoherence of Britain’s opposition parties. The SNP wants to leave the UK and abolish the nuclear deterrent. Labour’s shadow defence secretary Nia Griffith, though strong in her critique of underspending by the Tory-led MoD, and in her commitment to the deterrent, lacks the political backing to make the case for a clear alternative defence strategy. So I will make it here.

Britain needs a defence posture focused on meeting the primary military threat: a mixture of cyber-warfare, assassinations, organised crime, propaganda and financial manipulation that is designed to render its underpowered conventional defence capabilities useless. We don’t want, or need, to fight Vladimir Putin: we simply need to deter his attempts to weaken our democracy; show leadership to a Europe full of tin-pot crooks; and redesign our armed forces in a way best adapted to meeting this threat, in this period, in this potential theatre of operations, which ranges roughly from Iceland to Alexandria.

This means overtly disavowing a strategy of global reach. Symbolic frigates and infantry battalions scattered across the territories of the old British empire may comfort golf club Tories, and pander to service traditions, but they are strategically worthless. The argument that, owing to globalisation, Britain’s security begins in the Singapore Strait is worth addressing: but one Type 26 frigate patrolling there is equal to no frigates at all. If you defend everywhere you defend nowhere.

Britain should concentrate its armed and security forces on the two tangible threats to the security of its citizens and to the stability of its democracy: jihadi terrorism and Russian hybrid warfare. We are well-equipped with intelligence and security forces to meet both threats. The Dreadnought-class submarine programme will ensure the essentially political nuclear deterrent is maintained.

But the conventional forces in between are too weak and their structure badly-designed. They are underfunded and insufficiently rooted in civil society. This, in turn, has consequences for the nuclear deterrent. Some argue the current naval and air assets surrounding it are too small to protect it. Others that the weakness and unsuitability of our conventional forces make us dangerously over-reliant on nuclear deterrence. Even if we increase defence spending to 3 per cent of GDP, the pressures of keeping a nuclear deterrent going would require hard choices about conventional forces.

In the 2015 defence review Cameron’s government designed a force structure for an unspecified future expeditionary war. I want British military thinking to disavow expeditionary wars of the type fought in the Falklands, Afghanistan and Iraq, and concentrate on defending Europe. But the forces Cameron’s government envisaged can be adapted to this new task. The UK will have a deployable force of around 50,000 personnel with lighter and modernised armour, a lot of hi-tech weaponry, a big special forces capability and an aircraft carrier with a lot of F35 multirole fighters.

The question - and it is a political question - is where this force should be deployed and trained to fight - and where it should not. The main British military force should be focused on Europe and the North Atlantic. Not just in its equipment and training, but in its ethos. Since Iraq and Afghanistan, an entire generation of military leaders in Britain have grown up with a small wars culture: counter-insurgency, infantry patrols, special forces, language expertise in Arabic and Pashtun.

That, in turn, cascades over into civil society’s image of what a war is: heavily-armed British infantry patrolling villages in the dust. Sadly, this is about as far removed from the conflicts we will face in the 21st century as the Boer War was from D-Day.

The conflict we are engaged in is one where a semi-dictatorship intends to pollute our public discourse, destroy our democracy, flood our society with organised crime and buy its way into our institutions. Then, as it takes chunks of territory out of its neighbouring states, and reduces NATO to a talking shop, the rule-based geopolitical system gives way to one based on great power rivalry. At this point we had better hope that the other Western countries with serious armies are still democracies. But that is not a given.

Meeting Britain’s security challenges requires politicians to begin speaking straight language, not the risible waffle Williamson is prone to. Here’s how I would put it: we face a new threat but it is containable if we meet it calmly and maintain a credible deterrent force, both at the nuclear and conventional level. Our military needs significantly more money and support; in turn, its internal culture must become more reflective of the real Britain and we have to ask more of our young people to serve in the armed forces, either as regulars or reserves.

And we are going to need the political capability to design strategy. Despite the creation of a National Security Council, we lack a cross-party community of politicians, experts, academics and military capable of having an informed debate.

But having that conversation honestly means ceasing the Soviet-style bravado of the current administration. We cannot and should not be a “true global power”: we should be a major regional player in the defence of Europe against destabilisation and of our own society against terrorism.

Global reach was always a fantasy - with the same nostalgic origins as hard Brexit. As one evaporates, so should the other.