Washington is calling on Syria to remove its troops from the border with Turkey. Aid officials say hundreds of Syrians fled makeshift camps into southeastern Turkey as the military approached.
Ankara doesn't want to lose its economic engagement with Syria, but nonetheless is shifting its rhetoric in support of the people demanding more freedoms.
Turkey has long been fond of its geo-political position in the world. Foreign Minister Ahmet Davutoglu said in an interview with Al-Jazeera's English Chanel that when it comes to Syria, for instance, Turkey is uniquely positioned to help.
"Who else knows Syria today more than us," Davutoglu aksed. "Who can contribute more to a peaceful process in Syria, or in Iraq, more than Turkey? Those who are far away, they have different, of course, perspectives. This is our geography."
But sometimes that geography can be treacherous, and with Turkish and Syrian troops suddenly lining each side of the frontier, analysts say tensions are higher than they have been in years.
Joshua Walker, a Turkey expert at the University of Richmond, says the last real tensions between the two countries were over Syria's support for the PKK, the Kurdish separatists deemed a terrorist organization by Ankara.
"This time around it's the other way around," Walker says. "The Syrians have come to the border and it seemingly is a signal to say 'let us deal with our own internal matters, we're going to deal with it.' There is potential here for some real serious problems to arise."
It would be difficult to overstate the stakes this Syrian crisis is putting at risk for both Damascus and Ankara. For Syria, Turkey is the vital economic lifeline, pumping in investment, creating jobs, giving the northern city of Aleppo in particular a taste of the benefits of international trade.
Analyst Hugh Pope with the International Crisis Group says southern Turkey and northern Syria have traditional family and cultural ties that allow Turkey to engage a state that most of its western allies prefer to isolate.
"The border towns all have very strong links with each other," Pope says. "There are actually relationships between tribes and clans along the border. And then you have the tens, perhaps even hundreds of thousands of people who have been visiting Turkey as the visa liberalization has taken effect. So there's a very broad set of relationships."
The stakes are high for Akara as well. Analyst Joshua Walker, on a visit to Istanbul, says for Turkey, Syria represents a gateway to what it hopes will become a new free trading zone in the Levant, which includes Lebanon and Jordan as well. It's a vision Ankara has invested heavily in.
"Syria is kind of the crown jewel of Turkish foreign policy," Walker says. "It's kind of the place that it all began. And if Syria crumbles, so too does Turkey's vision of zero problems with its neighborhood. You can have zero problems with a regime and its people if they're not at war with each other. What happens when there's a war between the regime and the people? You have to make a choice. And it seems clear that Turkey doesn't necessarily want to have to make that choice."
But there are signs that Turkey is making a choice. Turkish writer and analyst Mustafa Akyol says the rhetoric of Turkey's leaders has slowly but steadily grown more critical of the Assad regime, and more supportive of the Syrian people – at first on humanitarian grounds, but more recently endorsing their desire for democratic freedoms as well:
"Turkish policy is more and more realizing the importance of people, vis-à-vis the regimes, and that dichotomy is becoming more and more apparent right now," Akyol says. "There will be a shift for a greater emphasis to the people's rights and security.
Analysts say Syria has never responded well to pressure, but it does seem keen to keep its economic channel to Turkey open. The question is will that be possible if Damascus continues to rely on military force instead of reform in response to an uprising that shows no sign of disappearing.