In fact, Turkey did nothing. The full circumstances under which the aircraft crashed remain unclear. However, there is considerable evidence - not least from the information supplied by the US and Russia - that it was well inside Syrian airspace at the time of the incident.
Turkey was also disappointed at the lack of international action in response to the Syrian crisis. As the number of refugees crossing the border continued to grow, it began to push for a no-fly zone to enable the creation of 'safe havens' inside Syria, where people displaced by the fighting could be supplied with humanitarian aid. Turkish officials raised the issue in informal meetings with NATO colleagues, suggesting that the Alliance could take responsibility for enforcing a no-fly zone under a mandate from the United Nations Security Council. To their frustration, no NATO ally favoured the proposal. On 31 August, in an address to the UN Security Council, Davutoglu explicitly called for the creation of safe havens in Syria. He failed to gain sufficient support.
By mid-October, there were over 100,000 Syrians in refugee camps inside Turkey. Another 20,000 were believed to be staying with relatives on the Turkish side of the border, outside the official camps. In recent weeks, Turkey has frequently criticised the international community for not doing enough to support Syrian refugees on its territory. However, the government has continued to refuse to allow foreign aid organisations into the country, arguing that the international community should instead donate money to help finance the aid effort.
The Kurdish dimension
In July, Assad's forces began to withdraw from many towns and cities in predominantly Kurdish areas in northern Syria. Although some Kurds have fought alongside Arabs in the FSA, most Kurdish organisations have tried to distance themselves from the fighting and have focused instead on trying to create a de facto autonomous Kurdish region.
These Kurdish organisations include the Democratic Union Party (PYD), which is closely affiliated with the Kurdistan Workers' Party (PKK), which has been waging a violent insurgency for greater rights for Turkey's Kurds since 1984. The PYD has assumed responsibility for law and order in several Kurdish towns in Syria close to the Turkish border and has resisted pressure from the FSA to join the armed struggle against the Assad regime.
The Turkish media has claimed that Assad is supporting the PKK and that the area under PYD control could be used as a platform for PKK attacks into Turkey. Erdogan has threatened to bomb areas under PYD control if they are used for PKK 'terrorist activity'. In fact, however, there is no evidence that Assad has provided assistance to the PKK. The PYD has repeatedly denied that it has any intention of allowing territory under its control to be used for PKK attacks. In reality, the terrain in the border areas under the PYD's control is flat and easily controlled, making it highly unlikely that the PKK would be able to infiltrate into Turkey from Syria even if it wished to do so.
Nevertheless, although the emergence of a Kurdish-controlled region does not pose a security threat to Turkey, it is a political challenge for the AKP. Even if they are not attacking Turkey, PKK militants are now able to organise and spread propaganda with relative impunity in PYD-controlled areas. In the longer term, the consolidation of an autonomous Kurdish enclave in Syria - whether under Assad or a new regime - would make it more difficult for the AKP to continue to resist pressure from its own Kurdish minority for greater language rights and a measure of self-government; particularly given that an autonomous region in Syria would be the second Kurdish enclave in the Middle East after the Kurdistan Regional Government in northern Iraq.
Turkey's military options
After the downing of the F-4E Phantom, the Turkish army's presence along the Syrian border was increased. Mobile anti-aircraft systems were deployed, as well as additional artillery and armoured units. There was a similar increase in activity after the shell struck Akcakale on 3 October, as Turkey sent additional tanks, howitzers and troops to the area. On 4 October, the Turkish parliament approved a motion allowing the military to stage cross-border air and ground operations in Syria. On 8 October, Turkey deployed an additional 25 F-16 Fighting Falcon fighter aircraft from the west of the country to Diyarbakir, the nearest main air base to the Syrian border.
On 10 October, Ankara abruptly forbade all Turkish aircraft from using Syrian airspace. A Syrian civilian aircraft which was transiting Turkish airspace at the time on its way from Moscow to Damascus was forced to land in Ankara by two Turkish F-16s. Turkish officials accused it of carrying an 'illegal' military cargo, which Erdogan described as 'munitions'. This claim was later discarded. Turkish officials issued a statement saying that the cargo contained spare parts for radars. Both Russia and Syria have strenuously denied that the plane was carrying anything illegal. On 14 October, Turkey closed its airspace to Syrian aircraft.
Despite the rise in tensions, Turkey's military options are limited. NATO has announced that it will come to Turkey's defence if it is attacked by Syria. But it has also made it clear that it will not support military action initiated by Ankara. Turkey's military capabilities - both in terms of equipment and manpower - are superior to Syria's. But without NATO support, it would have difficulty staging sustained unilateral military action either to enforce a no-fly zone or to engage the Syrian military without suffering losses that would probably be politically unacceptable. There is very little public support in Turkey for military involvement in Syria.
Perils of momentum
There is no evidence that the shell that killed five people at Akcakale was deliberately aimed at Turkey. The most likely explanation is that it strayed off target during fighting between pro-regime forces and rebels close to the border. It was initially reported to have been a mortar shell, which would have meant that it could have come from either side. However, Turkish officials claimed that it had been fired by a D-30 122mm howitzer used only by the Syrian army. Turkish forces responded by shelling a Syrian artillery unit deployed close to Ayn al Arus, around 12km from the border.
The alacrity of the Turkish response, which occurred within minutes of the shell landing, and to the shells that landed in Turkey over the days that followed, suggest that little attempt was made to ascertain their origin. Indeed, the military made clear that its rules of engagement include shelling Syrian army positions in response to any shells that land in Turkish territory, regardless of who fires them, whether they inflict casualties, or are accidental. In practice, this has given the Syrian military the choice of withdrawing from territory close to the border or risking being targeted by Turkish artillery.
Recent events suggest that Turkey's policy towards Syria has entered a new and more aggressive phase. Ankara appears determined to increase the pressure on the Assad regime, raising the possibility of increased Turkish aid to the FSA and even artillery support, from inside Turkey, for FSA operations in Syria.
The likelihood of a war between Turkey and Syria remains remote. But the new impetuousness of the Turkish approach is a cause for concern. It would be a mistake to underestimate the AKP's frustration at Assad's continued hold on power, NATO allies' refusal to play a more active role in trying to overthrow him and the emergence of a Kurdish enclave inside Syria. Although it currently appears small, there is nevertheless a danger that sustained - or even increased - military tensions could generate a momentum that could drag Turkey deeper into a highly complex conflict from which it would be hard to extricate itself.
