The Syrian Kurdish issue, which intensified in the aftermath of the Syrian civil war and the collapse of Damascus’s political order, has emerged as one of Turkey’s most significant security and geopolitical challenges. The growing influence of Kurdish groups in northern Syria has heightened Ankara’s security concerns and contributed to a shift in Turkey’s foreign policy toward a more security-oriented and interventionist approach. This study employs a qualitative research design, drawing on document analysis and secondary sources to examine the relationship between the Syrian Kurdish issue and the evolution of Turkey’s foreign policy doctrine. Based on the theoretical framework of the Copenhagen School, the central hypothesis posits that the Syrian Kurdish issue has not only constituted a major security threat to Turkey but has also played a direct role in redefining its foreign policy doctrine by shifting Ankara’s orientation from soft diplomacy toward more hard-power and militarized strategies. The findings indicate that the post-Assad crisis in Syria has prompted a strategic shift in Turkey’s foreign policy from an emphasis on soft power to a greater reliance on hard power. This transition has led to the prioritization of political and security objectives focused on combating terrorism, preserving Syria’s territorial integrity, and influencing the country’s future political order. Moreover, it has reinforced Turkey’s emphasis on border security, increased the priority accorded to border protection measures, and encouraged a more interventionist foreign policy aimed at shaping regional geopolitical dynamics.