LONDON John Humphrys chose to launch his grand tour of the union from Frankfurt for BBC Radio 4's Today programme the other day, with a homily about the euro, integration and “momentum”. But if he started east and headed west, he would have come across some quite different challenges.

There he would have found Iran, causing collywobbles wherever summits convene; Iraq, a profoundly unsettled state; and Nato's Afghanistan, a disaster without end. Here are Israel, Gaza and problems that defy any rational conclusion. The east, in short, is a mess, a source of menacing instability just at the point where we deem our cultural boundary to run out.

If the EU is as much about peace and war as it is about prosperity, then the other great starting point for a tour is a country that is a Nato member, borders Iran and Iraq, and doesn't like dealing with Israel any longer. Turkey has always been important. Now it's critical.

Turkish deaths on the Gaza flotilla aren't why Ankara and Jerusalem have drifted apart, but are merely a symptom of growing antipathy. Turkey's refusal to join the sanction rush against Tehran tells the same story. And if the Greek Cypriots keep refusing to accept UN negotiation timetables, you can wave hopes of a Cyprus accord goodbye. Turkey will settle for a permanent base for its burgeoning regional power.

In all three cases, a common theme the failure of the west, and especially Europe, to fit Turkey into the scheme of things, exert influence over Israel, try other approaches to Iran, even lose patience with Nicosia's delaying tactics.

There is, palpably, no place for Ankara inside Europe. Merkel, Sarkozy and recession have seen to that. Therefore, Ankara must construct a place of its own, and already we see what that means a big military power breaking loose, a de facto nation of Islam by choice, seeking to lead those around it. An old empire stirring again.

As John Humphrys might say “What, no momentum?” Once the queue to slip inside Europe's redefined borders dwindles, just see what trouble awaits. Ankara semi-detached and forming its own alliances (with Iran and Syria for starters). Albania, Macedonia, Montenegro, Serbia, Bosnia, Croatia? Welcome to the old Balkans cauldron, where European membership is the recipe for a future that no longer seems possible. Welcome to Greece, the best and worst advertisement for Europe in that region.

Once you lose the Big Mo that held 27 capitals in thrall, you start to lose your bearings. Of course, it's easy enough to chirrup away on Today about the euro's problems, pretending that, at this end of Europe, it's only a question of “In or out?” (The BBC has never really got much beyond 'In or out?' as EU debate.)

But see what happens in moments of flux. Is Obama being horrid to us over BP? If we're not his special friend, then who are we? A mere fumbler on some faraway goal line. London needs Washington to give it a role. Knock that casually away, though, and look across the Channel to see why there's no role left.

A union stumbling and dividing doesn't spell stability for countries where brushfire inter-communal fighting is clear and dangerously present. A stalled economic future means more than a crumpled drachma back in your pocket. It means old Europe rising again.

The archduke won't be staying in Sarajevo any time soon. However, the spread of wacky sub-nationalist parties and wackier merchants of hatred is a boom political industry already. The perils for embattled democratic politicians trying to make sense of this murky world grow ever more intense.

In or out? We're in come what may, as there's no chance of sitting this one out. The real question goes beyond the smirks of economists without momentum, what on Earth comes next?—Dawn/The Guardian News Service