Greece will not consider Turkey’s participation in the European Union’s emerging defense architecture for as long as Ankara maintains its 1995 casus belli (cause of war) in the face of any possible extension of Greek territorial waters, diplomatic sources said on Thursday.
At the same time, the sources drew a clear distinction between matters where Athens holds decision-making authority and issues that fall exclusively under US jurisdiction.
Diplomatic circles dismissed suggestions that Athens could exercise a “veto” over a potential US sale of F-35 fighter jets to Turkey, arguing that any such decision rests with Washington and the US congressional approval process rather than with NATO allies. They emphasized that while Greece can influence collective decisions within organizations in which it participates, it cannot dictate the defense procurement policies of third countries.
The distinction, the sources said, is fundamental to Athens’ approach. Greece has consistently argued that the Turkish acquisition of F-35 aircraft remains subject to existing restrictions under US law following Ankara’s purchase of the Russian S-400 air defense system, while Prime Minister Kyriakos Mitsotakis reiterated after this week’s NATO summit that significant legal obstacles remain. He also described Turkey’s longstanding casus belli as a “historic anomaly” incompatible with efforts to improve bilateral relations.
By contrast, Athens maintains it possesses a direct role in European defense initiatives, particularly regarding the EU’s Security Action for Europe (SAFE) instrument. Diplomatic sources said there could be no discussion of Turkish participation in European defense arrangements while the threat of war against Greece remains in force.
According to the officials, the SAFE regulation now requires a bilateral agreement between the European Union and any third country seeking participation, creating a mechanism through which member states may object. They described the inclusion of that provision as an important Greek diplomatic achievement that is expected to shape future European defense regulations as well. Recent reporting by To Vima has highlighted Athens’ view that lifting the casus belli remains a prerequisite for any substantial improvement in EU-Turkey defense cooperation.
Regarding Turkey’s revisionist “Blue Homeland” maritime doctrine, the sources said Greece would await any concrete Turkish legislative proposal before responding, while at the same time dismissing the concept itself as an ideological construct lacking legal foundation under international law.
The officials argued that the doctrine has harmed not only Greek-Turkish relations but also Turkey’s own international standing. Additionally, they stressed that Athens is not waiting passively, saying preventive diplomatic and legal measures have already been activated.
According to the sources, Greece possesses an extensive body of legal and diplomatic instruments, including European Council conclusions, decisions and resolutions adopted by international organizations, that could be deployed should circumstances require.
On maritime boundary negotiations, the officials said there is no immediate prospect of resuming substantive talks with Turkey because the two sides remain fundamentally divided over the scope of the agenda.
Athens continues to recognize only one bilateral dispute suitable for adjudication or negotiation: the delimitation of the continental shelf and exclusive economic zones. As long as Ankara insists on broadening the agenda to include additional issues, meaningful negotiations cannot begin, the sources said.
The officials also offered a broadly positive assessment of this week’s NATO summit, saying the meeting unfolded largely as expected, or even better than anticipated, with no significant tensions emerging among allies.
According to the sources, Greece’s role as a consistent and reliable NATO member was reaffirmed despite continuing strains across the transatlantic relationship. They also rejected suggestions that NATO’s collective defense commitment has weakened, insisting that Article 5 remains the alliance’s cornerstone.
The officials further denied reports suggesting NATO had discussed establishing alliance headquarters in Turkey. No such proposal appeared on the summit agenda, they said, explaining that any discussion merely concerns the possible use of existing national headquarters to support NATO operations during crises rather than the creation of new alliance structures. To Vima reported this week that Athens viewed the summit as underscoring NATO cohesion while continuing to monitor evolving US-Turkey dynamics over defense issues.
On Cyprus, diplomatic sources said Greece continues to support UN efforts to restart negotiations but acknowledged there is still no clear timetable for a new informal five-party conference.
They said UN Secretary-General António Guterres and his personal envoy remain engaged in consultations, while Athens continues to support a settlement within the framework of UN resolutions and the agreed basis for negotiations. However, the officials said they have yet to see indications that the Turkish side is prepared to alter its long-held positions on key issues.
Turning to Libya, the sources described contacts with the North African country as productive and said a visit to Athens by a Libyan technical committee is expected to be scheduled soon for a third round of discussions on maritime boundary delimitation.
Greece is also closely monitoring Libya’s internal political process, the officials said, supporting efforts aimed at forming a unified government and holding elections. They added that Athens remains in regular contact with the United States on developments in the country.
On the Middle East, diplomatic sources described the situation involving Iran as highly fragile, expressing particular concern over the security of shipping through the Strait of Hormuz. Greece is maintaining continuous consultations with Gulf states, the United States and Israel in an effort to maintain a comprehensive assessment of developments, they said.
Regarding Ukraine, the officials pointed to an escalation in Russian attacks, including strikes against civilian targets, and said they expect international attention to refocus on efforts toward a peace initiative once the immediate Middle East crisis stabilizes.
The sources also rejected suggestions that Greece’s close relationship with Israel has become a diplomatic liability. They argued that the partnership provides significant strategic and geopolitical benefits while not preventing Athens from criticizing specific Israeli actions when necessary.
At the same time, they described Greece’s relations with Egypt, Jordan, Saudi Arabia and the Gulf states as stronger than ever, reflecting Athens’ broader strategy of maintaining close ties across the eastern Mediterranean and the Arab world.
Looking to southeastern Europe, the officials said Greece remains committed to the European integration of the Western Balkans. Athens is expected to host a Friends of the Western Balkans conference this autumn while completing a series of high-level visits throughout the region.
They expressed confidence that Greece’s forthcoming presidency of the Council of the European Union could help reinvigorate the enlargement process, noting that Montenegro remains the accession candidate closest to membership.
The officials added that preparations for the Greek presidency are significantly more advanced than at comparable stages in previous cycles, with staffing, policy priorities and parallel programs already largely in place.
On overall EU-Turkey relations, diplomatic sources said modernization of the customs union and visa liberalization remain major outstanding issues but acknowledged that little tangible progress has been achieved. They argued that expanding the customs union would effectively require Turkey to fully implement the EU acquis toward all member states, including the Republic of Cyprus, making any agreement particularly difficult under current circumstances.
