By Peter Apps, Political Risk Correspondent
LONDON | Sun Jun 24, 2012 1:48pm EDT

LONDON (Reuters) - While the exact circumstances remain far from clear, the shooting down of a Turkish warplane shows Syria's military to be capable, extremely jumpy and increasingly drawn into confrontation with its most powerful neighbor.
That could prove a major deterrent for Western powers in particular, who want President Bashar al-Assad gone but are unwilling to risk troops or aircraft in a military intervention. Equally, they are wary of triggering a wider regional war.
Turkey says its F4 Phantom reconnaissance jet was engaged in testing the domestic Turkish radar system when it entered Syrian airspace by mistake. But Ankara is adamant it was firmly back over international waters when it was attacked without warning. Syria says the aircraft was firmly within its airspace and approaching its coast low and fast.
Exactly what the jet's true mission was remains far from clear. While Turkey says it is not unusual for planes to drift across national boundaries when on missions or exercises, the dangers of straying into Syrian airspace at such a time of tension would have been very apparent.
Having complained repeatedly that Syria's escalating conflict was crossing its borders, with thousands of refugees fleeing and occasional cross-border Syrian artillery and small arms fire, Turkey is widely believed to be increasing its support for Free Syrian Army (FSA) rebels on its soil.
The downed jet, some believe, may have been on a reconnaissance mission for the rebels or possibly trying to probe Syria's Russian-made radar and air defenses. With Western and Arab powers increasingly actively trying to bring down Assad, some analysts say almost anything is possible.
"What all this tells us is that there are a lot of "fishy" tactics and strategies going on in the region, with numerous players behind many curtains," said Hayat Alvi, lecturer in Middle Eastern studies at the U.S. Naval War College.
"The Syrian military has reason to be jumpy, given these circumstances. Nonetheless, the idea that it would be in Turkey's and Syria's respective national interests to engage in military conflict with each other is not plausible. Both sides would have too much to lose, and very little to gain."
Friday's incident underlined the fact that should foreign powers hope to repeat the kind of military intervention that toppled Muammar Gaddafi in Libya, it would first require an overwhelming assault on Syria's air defenses.
Foreign militaries may well now feel they have little choice but to keep a more respectful distance from Syria's borders, aware that even sophisticated high flying U.S. spy planes or pilotless drones could prove vulnerable.
"It's clearer that this was... a reconnaissance jet - reinforcing my view that this was a surveillance flight, and therefore suggestive of a bolder Turkish effort to step up the pressure and assist rebels," said Shashank Joshi, senior fellow and Middle East specialist at the Royal United Services Institute.
AVOIDING ESCALATION?
Turkey denies the jet mission had anything to do with the situation in Syria. The two countries initially cooperated in the search for the aircrew and wreckage in what appeared to be a deliberate strategy to avoid further escalation.
Ankara says the aircraft was clearly marked as Turkish and Syrian claims that they did not know its nationality when they fired were not convincing.

"Understanding the circumstances of the incident is crucial in informing Turkey's response especially as the region may ignite with hasty knee-jerk reactions," said Anthony Skinner, regional analyst for political risk consultancy Maplecroft. "This is something which (Turkish Prime Minister Tayyip) Erdogan, who is not one to pull his â