The threat is: Naive complacency, fuelled by geo-political ignorance, stimulated by misinformation and perpetuated by pacifist groups who have become very active in political circles.
In one of the most prosperous countries of the world, where malnutrition has been banished and given way to obesity as the main health hazard, where poverty is judged not on basic needs but on what the 'guy next door' is getting, where individual right is pre-eminent and the questioning of authority the norm, that hasn't had war inflicted upon it for the last 3 generations, where any potential foe is deemed to be a long way away and partly because of that distance they don't seem to be all that threatening; the mention of 'a threat' often raises an eyebrow and offers the question of 'what threat'? The apparent inability of the establishment to categorise the threat in the one or two sentence sound bite beloved of the popular media, leaves the way clear for very active pressure groups to put forward their belief that the maintenance of armed forces in general and the nuclear deterrent in particular is nothing more than militaristic aggression that is both unethical and a waste of money.
The threat has a multi-faceted complexity and to understand it you must first consider how this secure and benign environment in which we live has been achieved; beyond that how it is maintained and only then will the threat become apparent. Our wealth has been derived from commercial activity and trade, gradually increasing over the centuries and developing alongside the institutions which govern our society and the rule of law that sets the standards by which we live. The generally secure environment, within which all of these have been able to thrive, has been protected by the force of arms and at times by our forebears fighting and sometimes dying in foreign fields. While the struggle to maintain this benign environment may not be as intense and all consuming as it was in decades past, it goes on to this day.
The struggle to establish and then maintain this secure and stable state of affairs has not been achieved by the UK's efforts alone. We have been very successful in the nurturing of friends and allies (oldest alliance in the world = England/Portugal circa 1373) who broadly share our way of life and have helped to develop a network of democratic nations which sustain the status quo. This global network of inter reliance depends upon many things for its cohesion and not least among these are military alliances and agreements. Although the UK may not now be the most powerful nation on earth, her position at the head of the commonwealth, status within the United Nations, voice in the EU, history of stable government, backed by a constitutional monarchy with 3 further generations of legitimate heirs ready to take over (which is an insurance policy against extreme political adventurism), an economy that has not defaulted for 700 years with the oldest working currency in the world and a record of supporting friends and allies when they are in need, give her an influence that belies her size. Despite what some critical groups may claim, the maintenance of a strong military stature is one of the things that our friends and allies see as our commitment to the overall security of this family of nations. A scaling back of that ability will be seen by some as a loss of commitment to our common security and by others as weakness.
Our armed forces help to bolster not only ourselves, fourteen sovereign territories with 2.3 million square miles of ocean (excluding Antarctica) and NATO but also through article 42.7 of the Lisbon Treaty, all of the EU; all of the commonwealth who may call upon us for support and by default through them, other nations with which they have defence agreements. Those defence interests span the globe and while it may no longer be true to say that the sun never sets upon the British Empire, it still shines continuously upon the UK's responsibilities. While we in the UK sit comfortably on the eastern edge of the North Atlantic with, in one direction, the whole of Europe as a buffer between us and Russia, the Middle east and Africa and North America acting as a breakwater in the other direction, to the troubles of Asia, many of our friends and allies do not have the same isolation from problematic neighbours. From our standoff position however, with our multi layered defence force, all the way up to the nuclear deterrent, we give support and act as a reserve that strengthens the whole network of like minded nations and in a way, because of our distance from the 'wire', that is not immediately threatening to nations that lie outside our network of friends. The UK's forces therefore act as a stabilising influence so that we can all maintain the status quo of peaceful watchfulness and respect for what we and possible foes are capable of.
The long term threat of course is that the network unravels; the nations closer to what they deem to be immediate threats experience a surge of militaristic necessity and arms races, including possible nuclear proliferation ensue; with the world becoming a far more dangerous place. The UK's military is one of the elements that maintain the present stability and people should not delude themselves into thinking that the world geo political chemistry will remain unchanged if it is taken out of the mix. Consider the previously put question of why the UK does not have carrier battle groups? Answer - because the Americans have them and we are in an alliance. When the previous UK government came to power in 2010, had it not been for contractual fiscal penalties, the indications are that they would have cancelled the building of the two Queen Elizabeth aircraft carriers and for virtually the whole period of that government their fate was in question. Following the announcement that the US was pivoting its forces towards the Pacific and putting less emphasis on European defence, there is now a commitment to complete both carriers and bring them into full service. The bolstering of the UK's armed forces in that way emphasises a commitment to the common defence, helps to keep our main ally, the US, on board and shows the militarily less capable nations that we still have the capability to stand by them. If we reduce our capability and the US, sensing a failure of commitment, turns her back on European defence, what would the result be? Would the Germans for example, who can see a resurgent Russian military flexing its muscles and who in response have decided to increase their tank numbers by almost 50% but who also presently shelter under the nuclear umbrella provided by us, decide that they must take a much stronger military stance!!? What of the nations even closer to the east/west divide; the 3 NATO Baltic states are currently feeling extremely exposed?
By preparing for war we are ensuring peace and it is not an exaggeration to say that the immediate threat is that a misinformed and disinterested public may allow elements within the British political scene to emasculate the UK's forces, which could act as the catalyst for world instability. It is time for the establishment, i.e. Government, MOD and interested parties, to step forwarded, challenge the misinformation that is being transmitted through various media and educated the UK public to the truth of what our armed forces stand for and what they achieve. If they do not, then 'Naive Complacency' may increase and instability follow.