Of all the ministers who have been tasked with slashing their budgets, perhaps none have faced such impossible dilemmas as Defence Secretary Liam Fox. There is no possible combination of cuts that does not put the lives of our serving men and women, or the future security of Britain, directly at risk.

The Strategic Defence and Security Review would be difficult enough to compile even without the current economic pressures. A recent MoD document, ‘The Future Character of Conflict’, takes a snapshot of the world’s political and military balance in 2014 and 2029. The forecast is a catalogue of exponentials: more fields of conflict, many of them in space and cyberspace; state adversaries that are better adapted and better prepared to exploit the West’s weaknesses; greater threats from non-state groups who are increasingly difficult to differentiate from civilians.

The evidence of this is obvious. The Stuxnet virus that attacked Iranian nuclear facilities over the summer was a cost effective way for an anonymous government to slow the country’s progress towards building the bomb. The Iranian government has adapted its military operations to avoid direct competitions of firepower with the West, for example by supplying insurgencies and building a fleet of small attack boats that would ‘swarm’ larger Western vessels. Non-state adversaries are likely to proliferate as countries such as Somalia and (heaven forbid) nuclear-armed Pakistan face total or partial collapse.

Given the likely increase in non-state threats, some have argued for fewer ‘big ticket’ items such as aircraft carriers, fighter jets, and a nuclear deterrent, in favour of a greater focus on intelligence and the incisive capabilities of ground forces. Yet, potential wars between states are notoriously difficult to predict, and require such equipment to be at the ready: a major misjudgement of Defence Secretary John Nott was to table drastic cuts to the Navy just before the Falklands War.

Credible nuclear deterrents are essential, not only for preventing nuclear action from particular governments like the increasingly unstable regimes of Iran and North Korea, but also for keeping advanced nations from conventional wars of mass slaughter. America provides a ‘nuclear umbrella’, but how much cover this provides depends on an adversary’s perception and the US’s resolve, which can change with each new Administration. A small percentage of GDP spent ensuring the absence of total or nuclear war makes an independent nuclear deterrent seem cheap. Our armed forces need everything they’ve got.

The most expensive project is also the only one to have been ring-fenced by Fox. The replacement of Britain’s Vanguard class submarines, the current platform for Britain’s nuclear deterrent, will have an estimated capital cost of £20 billion (nearly half the annual defence budget), and most alternative deterrents have significant flaws. Both land and air launched deterrents need fixed facilities which could conceivably be neutralised by a pre-emptive nuclear attack, and an attempt to base these weapons abroad would face obvious and immense opposition.

One option would have been to convert the smaller, stealthy Astute class attack submarines still under production to fire Tomahawk cruise missiles tipped with nuclear warheads. Each Astute costs just over £1 billion and the savings would have dwarfed the additional conversion costs. Some of the money saved could have been put towards extending the planned Astute fleet, creating jobs, and more platforms for a greater deterrent. Tomahawks have a shorter range of 1000 miles, and critics argue that there is a greater chance of them being intercepted. However, it seems unlikely that a foreign government would feel confident in making belligerent moves because it only has a chance of eliminating our response, particularly when it doesn’t know where that might come from or in what numbers.

Liam Fox has played it safe: he’s chosen Trident. But as the release of the Strategic Defence Review nears, we can only wait with trepidation to see how this will affect the future capabilities of the rest of the UK’s Armed Forces.