Given the various crises afflicting the EU, it would be easy to forget that NATO, Europe’s second organisational pillar, has serious problems of its own. The summit in Warsaw will put on a good show of allied resolve – but several problems are hanging heavy over it.

The first, and most embarrassing, is the fallout from the UK’s EU referendum. Several NATO leaders, Barack Obama among them, used up valuable political capital in backing the Remain side. Secretary General Jens Stoltenberg warned that a Brexit would be “bad news for NATO”. And as for the British Conservative Party’s contest to choose the next leader and prime minister, the leading candidates have reminded the British public that a post-Brexit UK is still committed to the alliance – but London’s political stock with its major allies has fallen dramatically, and could yet fall further.

Hard feelings in Paris, Berlin and Rome over the timing and terms of a Brexit is likely to undermine the alliance’s solidarity. The UK’s close strategic relationship with Poland will suffer as the large Polish community in the UK is unsettled by rising English nationalism. And Washington will look askance as talk of a post-Brexit Scottish referendum on independence opens up, once again, the possibility of the UK’s submarine-based nuclear deterrent having to relocate from the Clyde estuary.

The UK’s European military leadership role is also at risk. According to recently-released data, the UK is one of just five allies which meets NATO’s target of spending 2% of GDP on defence. But military spending could be a soft target for whoever is the UK chancellor of the exchequer once the anticipated Brexit-induced budget crunch arrives. The UK’s premier role in brokering the NATO-EU relationship could also become vacant.

Troubled times

An internal rift could not have come at a worse time, as the alliance is challenged on many other fronts.

NATO still has a mission in Afghanistan, and it’s helped keep the Taliban out of Kabul. But as with the earlier and much larger International Security Assistance Force mission, it hasn’t made much progress on achieving nationwide stability there.

Meanwhile, the alliance has simply opted out of the arc of crisis that stretches from the Middle East across North Africa. The anti-Islamic State coalition benefits from the “hidden hand” of NATO interoperability, but other than lining up NATO AWACS aircraft, a formal role for the alliance remains absent, subject to major disagreements of approach between NATO allies Turkey and the US.

In the Iraq/Syria theatre, NATO can at least claim it has no precedent or mandate for involvement – in the week the Chilcot report is published, recall that it was not NATO which became embroiled in Iraq but rather a US/UK-led coalition of the willing.

To NATO’s east, the luxury of choice is not available. NATO’s 2014 summit was dominated by the implications of Russia’s annexation of Crimea and destabilisation of eastern Ukraine; two years on, NATO will continue with the plethora of measures it has implemented to reassure its Baltic and Black Sea allies.

They are not sufficient. NATO’s “enhanced forward presence” represents only a small fraction of the forces Russia has been building up. While a Russian military intervention in the Baltic States may be unlikely, should it come to that, the combined conventional forces of NATO would be hard-pressed to resist.

This threat means NATO has had to revisit its nuclear strategy, but there’s still no consensus on what the next steps should be. Poland is reportedly in favour of giving greater prominence to NATO’s nuclear dimension; Germany is against it. Angela Merkel has argued that a resumption of political dialogue with Moscow is the only way out of this strategic dead end.

The NATO-Russia Council will meet a week after the summit, but with low expectations. NATO is refusing to budge on two of Moscow’s concerns: the deployment of NATO missile defence on the one hand, and continued enlargement on the other. The alliance has sensibly avoided offering membership to Russia’s neighbour Georgia, but Moscow still rails against NATO’s policy of an “open door” to possible new members, dismissing it as a thin cloak for aggressive expansion.

The great unravelling

Stretched, divided and under pressure, could NATO fall victim to the great unravelling of the European order?

The alliance has previously shown great resilience in times of trouble. It recovered from deep divisions over Iraq in 2003 and held together during more than a decade of combat in Afghanistan. The shape of the institution also matters: NATO doesn’t have the intrusive quality that’s alienated European electorates and political elites from the EU.

But challenges without and within could still be its undoing. Escalation by stealth on Russia’s part could test NATO’s resolve in the Baltic States – driving it not to war, but to an appeasement that would damage it irreparably. And in a true nightmare scenario, upcoming presidential elections in the US and France could see Donald Trump and the Front National’s Marine Le Pen take power.

Can NATO survive these threats? It’s not yet “the last European institution standing”, but its importance has nonetheless increased. The Warsaw summit will be a show of cohesion and strength – but the real tests are still to come.