By day, the Kilis border crossing between Turkey and Syria is bustling.

Cars, vans, minibuses drive back and forth, families spilling in and out, unloading their wares, or packing up as many of their belongings as they can.

Others walk the long road, dragging bags and suitcases, bundles strapped to their backs, sometimes propped on their heads.

The Kilis refugee camp, where 12,000 Syrians live in metal containers, is just off the side of the main gate. Its temporary residents regularly step out for a change of scenery, a ride to the city or the occasional interview with reporters in the parking lot across the road.

At night, the crossing is mostly deserted. It is dangerous to travel after dark.

Here with our CBC reporting team, I walked that road recently to the last Turkish checkpoint. The guards at the first of two gates sat inside their booth, escaping the night chill, engaged in heated discussion.

"Your prime minister is an idiot," one guard poked the other, presumably a supporter of Turkey's leader, Reccep Tayyip Erdogan.

"Twenty years ago, you wouldn't have heard that here, you couldn't say that openly," said Aziz, our Turkish producer, laughing out loud, loving the change. "That’s what they're fighting for in Syria."

That, and then some.

Enter the Kurds

Over the course of almost 20 months, the fighting in Syria has escalated from uprising to armed rebellion to a civil war that threatens the security of the entire Middle East.

It has been labelled everything from a new Cold War between Russia (and China) and the West, a proxy war between Shia Iran and Sunni Saudi Arabia, and a new front for al-Qaeda.

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The Turkish goverment has been rattling sabres, but thousands of Turks took to the streets of Istanbul last month to protest against getting more involved in the Syrian crisis. The banner reads No war of imperialism with Syria. (Associated Press)

Religious rivalries between Syria's majority Sunni population and the regime's ruling Alawites — an offshoot of Shia Islam — have been exacerbated by a steady stream of foreign fighters flocking to both sides of the battlefield.

And now, a further escalation is threatened by the nation-seeking Kurds — ensconced in Syria, Turkey, Iraq and Iran — suddenly deciding to join the fray.

Syria's Kurds make up about 10 per cent of the population, and they are long-time opponents of the Bashar al-Assad regime.

Until now, they have largely kept out of the conflict, which has left over 36,000 dead.

But last Friday, armed members of the Kurdish Democratic Union Party (PYD) clashed with the opposition Free Syrian Army fighters (FSA) who were trying to take control of a neighbourhood in Aleppo.

Hundreds were kidnapped from both sides, presumably to be held as hostages, and skirmishes continued in the neighbouring countryside for days.

Turkish media referred to this latest development as the most important, and most troubling of the recent failed ceasefire, brokered by the UN envoy for Syria Lakhdar Brahimi.

A tangled web of alliances explains the concern.

Turkey embroiled

The PYD is the sister party to Turkey's Kurdistan Worker's Party, better known as the PKK, militants who have been fighting successive Turkish governments for 25 years to carve out an area of self-rule in southeast Turkey.

The Turkish government considers them a terrorist organization and has thrown many of them in jail, where they have embarked on a months-long hunger strike.

At the same time, the Erdogan government has been the strongest international supporter of the Syrian opposition and the FSA since the onset of the conflict.

It has offered safe haven to the regime's military and political opponents, and led the diplomatic charge against al-Assad and for NATO to become involved. 

Fighting between the FSA and militant Kurds in Syria, then, represents an expansion of Turkey's internal struggle with the PKK and adds an element of ethnic strife to an already anarchic battlefield.

It also opens the door to the possibility of a new front, one that would distract from the fight against the regime, and that might drag Turkey even deeper into the conflict.

Cross-border shelling

Tensions between Turkey and Syria, once close allies, have been particularly high since June when the Syrian military downed a Turkish fighter jet.

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Syrian troops launched mortars into the Turkish border town last month, killing five civilians and provoking nearly a week of cross-border retaliation. (Associated Press)

Then, last month, a mortar bomb from Syria exploded in a residential neighbourhood in the Turkish border town of Akçakale, killing five people and wounding others.

The Turkish Parliament quickly passed legislation allowing the military to retaliate and sporadic shelling and gunfire have been exchanged across the border ever since.

War talk was rampant for a few days, but it was soon quelled. Large street protests erupted against a possible war with Syria, while other demonstrations have pitted police against Kurds supporting the imprisoned hunger strikers. Tensions are riding high on many fronts.

A member of NATO, Turkey has always been in a unique position, and is again now, perhaps more than ever.

A former imperial power (the seat of the Ottoman Empire) it is now a staunch Western ally that maintains political and economic ties with Iran and Egypt’s Muslim Brotherhood.

It ceaselessly fulfills the rather tired adage of being the place where East meets West. 

At the same time, its prime minister, Erdogan, is a divisive figure to many. He often talks tough, bullies and grandstands, exhibiting a Middle Eastern macho that is seen by many here as charismatic, but that translates poorly in other parts of the world.

His crackdown on the Kurds, and journalists alike, have merited Turkey one of the lowest human rights rankings of any democracy.

And yet he relentlessly jockeys for central stage in the Middle East, trumpeting Turkey as a model for the nascent democracies of the region.

Erdogan is something of a puzzle to the West, and never more so than when he strikes out on his own, as he did again last week.

Turkey's foreign minister, Ahmet Davotoglu, announced that Turkey ruled out any dialogue with the Syrian regime, which runs against the grain of the ongoing international negotiations, which continue to seek a political solution over any military intervention.

But then, Turkey is unique in that it shares such a long, over-800 kilometre border with Syria, and from almost every perspective — geographical, economic, political alliances and influence — the stakes are simply higher here.

The government has now heavily fortified the border – moving troops and tanks all along the frontier – and the military has struck back at the Syrians more than a few times of late.

The Turkish government says it is arming itself for the sake of deterrence, a position welcomed by most Turks who look to Syria with concern, but with little desire to get any more involved.

The chaos of this conflict, however, and the recent entry of the Kurds, will certainly continue to trouble this fine balance.