of the Imia crisis, the Turkish government widened its argumentation to include not only Imia but also a possibly large number of other islands and small formations across the Aegean. Since then, Turkish authorities have spoken of "grey zones" of undetermined sovereignty. According to the Turkish argument, these islets, while not explicitly retained under Turkish sovereignty in 1923, were also not explicitly ceded to any other country, and their sovereignty has therefore remained objectively undecided. The Turkish government has avoided stating exactly which islets it wishes to include in this category. On various occasions, Turkish government sources have indicated that islands such as Pserimos, Agathonisi, Fournoi and Gavdos (situated south of Crete) might be included. Most of them, unlike Imia, had undeniably been in factual Greek possession, which had never previously been challenged by Turkey, and all but the final two listed below have Greek residents and infrastructure. Furthermore, the islands are covered by previous treaties such as the Treaty of Lausanne, which defines Turkish sovereignty as limited to within 3 miles of the Anatolian mainland in the majority of cases. In a 2004 publication by Turkish authors close to the Turkish military leadership the following (among other, even smaller ones) were listed as potentially "grey" areas: Oinousses (between Chios and the Turkish coast), Antipsara (west of the islands of Psara and Khios), Fournoi, Arkoi, Agathonisi (Gaidaros), Pharmakonisi, Kalolimnos (near Imia), Pserimos, Gyali (between Kos and Nisyros), Syrna (SE of Astypalaia) Kandheliousa (south of Kos), Kalogeroi (islets) (small rocks 41 km northeast of Andros) Military overflights over Greek territory While Turkey has not attempted to challenge Greek sovereignty on the ground, its claims about "grey area" islands add to the number of minor military incidents, already numerous due to the 10-mile airspace and the FIR issues. Greek authorities routinely report that the Turkish Air Force ignores their national airspace. According to Greek press reports, the number of airspace violations rose sharply in 2006, as did the number of unauthorized Turkish military flights directly over Greek islands themselves. Renewed reports of systematic Turkish military flights directly over Greek islands like Pharmakonisi and Agathonisi were made in late 2008 and early 2009. During the late 2010s, tensions rose again as Turkish fighter aircraft increased the number of direct armed overflights above inhabited Greek islands. While most overflights continue to occur above small islands that Turkey considers "grey areas", such as Agathonisi or