If you think that the North Atlantic Treaty Organization – the mutual-defense alliance founded in 1949 – is one big, happy family, you'd be wrong.
There have been deep tensions between NATO countries in the past. For a while, France was not even part of the military structure.
Then, there's Greece and Turkey. To say they have provided a bit of intra-alliance drama is one of the biggest understatements in the existence of NATO.
Greece and Turkey have had a fair amount of historical animosity. In 1897, the two countries went to war, after which Greece secured the autonomy of Crete. From 1919-1922, the two countries went to war again. Turkey won that second round, pushing Greece out of Asia Minor for the most part.
A Hellenic Air Force Mirage 2000EG. (Photo from Wikimedia Commons)
In the 1950s, the Cyprus issue renewed tensions despite both countries' memberships in NATO, as did maritime territorial disputes in the Aegean Sea, leading to a near war in 1987, according to the New York Times.
A March 1996 report by the Congressional Research Service described the Imia/Kardak Crisis of 1995, another near-war.
War loomed again in the Cyprus Missile Crisis of 1997-1998, with the Independent reporting Turkey threatened strikes against Russian S-300 missiles sold to the Greek Cypriots. That crisis wasn't defused until Greece bought the missiles and based them in Crete.
In the past year, the maritime territorial dispute in the Aegean Sea has heated up again, thanks to Turkish President Recip Tayyip Erdogan, according to recent news reports.
Land-based S-300 surface-to-air missile launchers | Creative Commons photo
So, what would happen if Greece and Turkey went to war? History can be a guide.
Past crises have usually seen NATO apply a lot of diplomatic pressure to avert war. The North Atlantic Treaty, in fact, gives NATO a very big vice to apply that pressure.
There have been incidents between the two countries in the past where troops have exchanged fire planes have been shot down. So, while wars have been averted so far, the possibility remains that an incident could prompt a full-scale war between these two NATO allies.