A Turkish F-16. Wikipedia Commons A formation of Turkish fighter jets violated Greek airspace a total of 20 times on Wednesday before being chased off by Greek aircraft, Kathimerini English reports.

A total of six Turkish fighter jets flying in formation carried out repeated violations of Greek airspace, according to the newspaper, which is one of the most respected in Greece. The reported violations took place in Greek airspace over the north, central, and southern Aegean Sea.

Citing Greek defense officials, Kathimerini reports that two of the Turkish jets were carrying armaments and that a tense close-quarters confrontation occurred between the neighboring countries' jets.

Airspace violations between Greece and Turkey are a common issue between the two countries, especially over the Aegean Sea. The island-filled stretch of water separating Turkey and Greece contains maritime boundaries that are a persistent source of disagreement between the two countries.

"The question of sovereignty over the Aegean in simplest terms is the difference between Greek territorial waters of six nautical miles and the 10-nautical-mile airspace Greece claims," Metin Gurcan writes for Al-Monitor. "The conflict arises when Turkey recognizes the Greek national airspace over the Aegean as six miles and flies its planes within the 10-mile airspace claimed by Greece."

Although violations happen with frequency between the two countries, Turkey and Greece have seen a rapid increase in incidents since 2013. In the first month of 2014 alone, Turkish aircraft allegedly violated Greek airspace 1,017 times, Gurcan reports. This was twice the number of total airspace violations between the two countries for the first half of 2013.

Airspace violations have actually become so routine between the two countries that Turkey now lists all incidents under the "Daily Activities" section of the chief of general staff website.

The incidents reflect the still-ongoing hostility between Greece and Turkey. Both countries are NATO member states, but are divided over the Cyprus conflict, with Turkey being the sole country to recognize the Turkish Republic of Northern Cyprus as an independent state and Greece advocating Cyrpus's control over the entire island. Oil and natural gas deposits around Cyprus have also become a major point of contention between the countries.

This distrust of Turkey is so deeply routed that it is one of the primary reasons that Athens continues to devote a larger share of its GDP to defense than almost any other NATO nation despite its ongoing budgetary issues.

The 2.4% of GDP that Greece is projected to spend on defense in 2015 is actually a sharp decrease from the country's previous spending habits. Throughout the 1980s, Greece's average defense budget was 6.2% of its GDP largely due to tensions with its Turkish neighbor.