Photo: Major Paul Smyth (crown copyright)

By 2020, the government will have cut the British Army from 102,000 to 82,000. The security and defence review acted as if Iraq and Afghanistan were the last big wars that Britain would fight. The assumption appeared to be that a conventional war, or even a sizable conflict in Europe, is now unthinkable.

But it isn’t. The future stability of Europe should not be taken for granted. Around its border there are threats to European security of such significance that Britain must fundamentally rethink its current defence strategy.

To the east, Russia under Putin is unstable. It suffers from a profound economic weakness in its reliance on oil exports. In order to balance its budget, Russia needs to sell its oil at between $110–$120 a barrel. However, recent discoveries across the globe of cheap deposits of gas are reducing demand for oil and depressing oil prices. Alexei Kudrin, Russia’s former finance minister, warned earlier this summer that Russia should brace itself for a drop to around $60 per barrel. That would drain Russia’s reserves within months; in reaction, and under pressure from resurgent nationalists and communists the Kremlin beset by domestic instability might try to win popular support by reasserting its influence over its “near abroad.” In August, Putin admitted to approving the 2008 invasion of Georgia two years in advance. Under his leadership Russia has extended its influence over Belarus, Ukraine, and even Bulgaria through economic and political ties.

Ukraine is particularly tense, with its age-old division into a Ukrainian speaking west that looks to Europe, and a Russian speaking east that looks to Moscow. In August, when Victor Yanukovych, the pro-Putin president, signed a law allowing regions to select their preferred official language, there were riots in Kiev. Protestors saw it as a ruse to give Russian official status. Meanwhile Belarus, a country that remains jammed in the Stalinist deep-freeze, saw popular demonstrations in late 2011. An unstable Russia with an equally insecure near abroad is entirely absent from current UK and European Union strategic assumptions. If there were a popular revolution in Belarus what would Russia do and how would the west respond?

In Turkey, whose leaders and people were once desperately keen to join the EU, opinion has shifted. A survey in August by the Turkish European Foundation for Education and Scientific Studies found that the number of Turks now in favour of joining the EU stood at 17 per cent, a record low. The euro crisis is hardly an attraction, of course. But the result is that this crucial eastern neighbour sees little need to court Europe. During a CNN interview in September, Recep Tayyip Erdogan, the prime minister, commented regretfully that “there are certain things we expected from the United States,” which were not forthcoming in Syria. He did not mention even the possibility of European assistance. In short one of the vital security bulwarks of the EU has started to erode.

In Syria and across the southern Mediterranean shore, the Arab spring has yielded dangerous uncertainty. The murder in September of the US ambassador to Libya, Christopher Stevens, demonstrated the turmoil and the possible jihadist capture of nations in which revolutions were regarded as having succeeded.

And even if these Arab revolutions avoid tribal and sectional fracture and eventually lead to stable democracies, southern Europe can still expect waves of migrants streaming across the sea seeking economic opportunities. But the Arab spring could also become a harsh winter. A string of failed states lined up along Europe’s southern flank would be a security nightmare for European governments and an ideal operating platform for al-Qaeda.

Hanging over all of these scenarios is the possibility that Israel will launch aerial strikes against Iran’s nuclear facilities. Meanwhile, Tehran, well supplied with politicians of some diplomatic agility, has sent officials to Greece to explore whether it—and possibly Cyprus—might be customers for Iranian oil should Greece have to leave the euro.

And internal threats exist in Europe also—in the medium term solving the euro crisis risks consigning southern Europe to a generation of austerity, such that long-term politicised unrest seems probable. Even the UK’s very near abroad no longer looks so stable. Yet Britain’s strategic assessments take into account none of these threats. We are not prepared.