Turkey is holding the largest naval drill in its history with over 100 vessels on all three seas surrounding the country. The four-day drill, dubbed “Blue Homeland 2019,” began Wednesday with the participation of 103 navy ships in the Black Sea, the Aegean and the Eastern Mediterranean.

The flotilla includes 13 frigates, six corvettes, 16 assault boats, seven submarines, seven mine hunting vessels and 14 patrol boats, as well as other navy vessels, Daily Sabah reported.

The drill was planned six months in advance in line with NATO rules and regulations. It is coordinated by the Naval War Center Command and will last through March 2.

Blue Homeland comes at a time of tensions with regional countries over territorial waters. Turkey and Greece are at odds over rights in the Aegean Sea separating the two countries, although Athens and Ankara sought to defuse tensions with a recent visit by Greek Prime Minister Alexis Tsipras to Turkey.

Turkey is also concerned by Greek Cypriot attempts to drill in the Mediterranean Sea for natural gas and oil. Ankara argues that the Greek Cypriot side of the divided Mediterranean island of Cyprus is not entitled to unilaterally exploit resources in an area where Turkish Cypriots also have rights.

The drill, which aims to test and improve the preparedness of naval forces, started with ships leaving eight naval bases from the north to the south. It gives an opportunity for military units to try out operation plans in the locally developed Naval War Games System. A team of 165 military personnel will lead the nationwide drill.

Some highlights of the drill will be the new additions to the navy of the TCG Burgazada corvette to unmanned aerial vehicles (UAVs). The Burgazada is the third Ada (Island) class corvette built as part of the National Ship (MILGEM) project and delivered to the navy after TCG Heybeliada and TCG Büyükada, which were delivered in 2011 and 2013, respectively. The fourth corvette, TCG Kınalıada, is currently under construction and will be delivered in 2020.

The corvette, delivered last year to the navy, will join a drill for the first time. ANKA and Bayraktar, two UAVS which are already in use by other forces of the Turkish military, will also be tested in the naval drill. In cooperation with the land forces, the navy will also try out UMTAS anti-tank missiles and the domestically-produced CİRİT anti-aircraft missiles.