LONDON/ISTANBUL - Turkey may be some way from acting on Prime Minister Tayyip Erdogan's threat to strike Kurdish separatists in Syria, but week by week it finds itself sucked ever further into its neighbor's worsening war.
The shooting down of a Turkish reconnaissance jet last month was seen by many as a turning point, prompting Ankara to join Saudi Arabia at Qatar in semi-covert support for the Free Syrian Army fighting against President Bashar al-Assad.
On Friday, Reuters revealed the existence of a secret Turkish operations centre where it worked with the two Gulf states to provide aid and weaponry to the rebels.
For most foreign powers, events in Syria's Kurdish provinces are largely seen a sideshow compared Assad's battle to survive. But Erdogan's comments on Thursday made it clear that Turkey is alarmed by worries over Kurdish PKK rebels taking advantage of the chaos.
The Turkish leader - once a friend to his Syrian counterpart who helped to rehabilitate Assad on the international stage, but now apparently an increasingly implacable foe - accused Damascus of allocating five provinces to the PKK.
Both Ankara and most Western powers view the Kurdistan Workers Party (PKK) as a terrorist group, blaming it for a long-running conflict that has killed some 40,000 people since it took up arms in 1984. Turkey regularly strikes PKK bases in Iraq's northern self-ruled Kurdish enclave, and Erdogan made it clear the same option was being discussed for Syria.
"We will not allow a terrorist group to establish camps in northern Syria and Turkey," he told a news conference before travelling to London for the opening of the Olympics. "If there is a step which needs to be taken against the terrorist group, we will definitely take this step."
Rising numbers of refugees crossing the border could put further pressure on Turkey. If, as many expect, Assad's forces target the partially rebel-held city of Aleppo in the coming days, numbers could soar. Turkey has already closed its borders to commercial traffic but says it will allow fleeing civilians through.
Whatever might happen on the Kurdish front, a senior Turkish official speaking on condition of anonymity said support for the rebels was set to continue - although clear caution remains.
"Naturally we are watching developments in the Kurdish region, but Ankara will not give up on its support for the whole revolution because something has happened in the Kurdish region," he said.
"We have been saying from the start, we do not think it is right to impose a regime from outside... The Syrian people must decide its own future."
The official declined to comment on what Turkey might do if the PKK established itself in the region.
CROSSING RED LINES
What Turkey is desperate to avoid is a scenario in which Kurdish parts of Syria quietly break away from the rest as the government, rooted in Assad's Alawite minority sect, slugs it out with the predominantly Sunni Muslim opposition.
"Any area which serves as a potential haven for the PKK or its affiliated groups poses a direct threat to Turkish security and Ankara's jingoistic rhetoric should be judged in this context," says Anthony Skinner, head of the Middle East practice at UK-based security consultancy Maplecroft.
"Any government which allows the PKK to set up training camps represents a red line for Ankara.... Ankara is again warning Damascus not to cross Turkey."
But if it is to take military action, Turkey's options are somewhat limited. Turkey might have the largest military in the region, but a large-scale ground incursion is seen as unlikely for now.
An airstrike on a known PKK facility - or perhaps a Syrian government post believed supporting them - seems a much more probable approach. But while air defenses over Kurdish areas are seen as a much less sophisticated than those along the coast, the loss of one Turkish jet already points to the dangers of entering Syrian airspace.
"If Turkey could prove that there was an attack coming out of Syria against Turkey, then it could launch an air strike, if it could identify a specific PKK camp in Syria," said Istanbul-based security expert Gareth Jenkins. "The problem is there would inevitably be civilian casualties because these camps would be put near civilians."
Then, there is the risk of severe retaliation. Earlier this week, Syria's government said that while it would not use chemical weapons against its own people, it might against any foreign intervention.
"Unlike with Iraq, attacks in Syria can very likely draw Turkey into a prolonged military confrontation with the Assad regime, which has a formidable military and the political will to respond," says Hayat Alvi, lecturer in Middle Eastern politics at the US Naval War College. "Syria and Turkey are both heightening the rhetoric, but it would be a huge gamble for both sides to engage in military confrontation."
Turkish leaders have long regretted the way in which northern Iraqi Kurdistan effectively seceded after the 1991 Gulf War. At worst, Turkey now fears Iraqi and Syrian Kurdish areas might try to come together to form a larger Kurdistan - an entity that might yearn for swathes of Turkish territory.
SIMPLY SABRE RATTLING?
Already, commentators in Turkish newspapers express growing concern that that is exactly what is happening. What the PKK may end up running in parts of Syria, they say, may not just be assorted training camps but a de facto Kurdish state.
The image of PKK members directing traffic and performing other civic duties, some Turks worry, could help swell its support both amongst Kurds and more broadly. At the very least, the PKK would probably have access to both new recruits and some of the weaponry made available by Syria's wider and fast-growing conflict.
"The recent developments could provide the PKK with significant military opportunities. If the government doesn't take any precautions and wastes this most precious time, Turkey will face serious security problems," Nihat Ali Ozcan, a security analyst at the Ankara-based think tank TEPAV, wrote in Hurriyet Daily News.
"The PKK wants to harvest the political opportunities these military advantages would provide, will rise up and be more aggressive about reaching its aims."
Exactly how much support Syria might be giving Kurdish separatists is far from clear, although some Syrian opposition figures accused the PKK's local partners, the PYD, of acting as enforcers for Assad.
Under both Assad and his father, Hafez, Turkish accusations of Syrian backing for the PKK were points of contention and occasionally led to threats of outright conflict.
In 1998, Turkey moved tanks to the border and explicitly threatened to send them into Syria if Damascus did not expel PKK leader Abdullah Ocalan, at the time sheltering in Syria. Hafez al-Assad took the threat seriously enough to evict Ocalan - who was shortly afterwards captured in Kenya by Turkish forces and probable US support.
Some kind of at least tacit agreement from Washington might still be needed for the Turks to be willing to take action.
"The Turks have been going for a gold medal when it comes to sabre rattling," says David Lea, regional analyst for Control Risks, a consultancy firm.
"But someone - most likely the Americans - has been sitting on their tail. I don't think the Turks would do anything unless they knew the Americans were with them. They want to act, but they don't have any good options. It's a microcosm of the whole Syria situation."
(Reporting by Peter Apps; Editing by Peter Graff)