Aside from a military response, Ankara will be looking for other ways to pressure Damascus. One such response is cutting off electricity exports to Syria. The Turkish government has threatened such a measure before, and a final decision on the matter is expected in the coming days. Of course, halting electricity exports is less provocative than a military strike, and opposition groups within Turkey are using this perceived weakness to challenge Erdogan.
Domestic issues notwithstanding, Erdogan's measured response will add a new dimension to the Syrian unrest. Would-be defectors — even high-ranking Syrian officers — will be discouraged from entering Turkey if they are to be treated as enemy combatants. Moreover, the response will likely provoke more hostile engagements at the border. Such engagements, particularly those between Syrian rebels and Syrian armed forces, were never rare occurrences, but Turkey has never participated in them. Declaring incoming Syrian forces as military targets could change this dynamic.
For its part, Syria will face new challenges in light of Erdogan's response. If Damascus takes the warning seriously, the Syrian army will have a more difficult time engaging rebel fighters on either side of its border with Turkey. In turn, this could lead to increased rebel activity along the border. Aware that the Turkish military is authorized to engage the Syrian military, Syrian rebels could try to draw troops close to the border to force a Turkish response.
By working through NATO rather than responding unilaterally, Ankara secured international support for its response. Ankara also signaled to Syria's international allies its willingness to bring NATO into the region. However, the decision to refrain from offensive operations may prompt Syria's main allies, Russian and Iran, to increase their support for Damascus. By choosing a more measured response, Erdogan has eased the pressure on the Syrian regime directly, giving Tehran and Moscow an opportunity to funnel more military supplies to regime forces. The fighting between the government and rebel forces will continue and more international support for rebels may begin flowing in.