THE 70th birthday party of the North Atlantic Treaty Organization (NATO) has been a shambles. But then this Western military alliance has been showing its age for the best part of two decades. The problem has been that this alliance of 29 countries ran out of a reason to exist when the Soviet Union collapsed and the countries of Eastern Europe threw off the Communist yoke. The Soviet Union's Warsaw Pact dissolved with the Iron Curtain that marked the nervous Cold War frontiers. In the late 1990s, after the old Soviet empire had fallen apart, there was a reasonable argument that NATO could be wound up. It had indeed never fired a shot in anger at the enemy, but had trained vigorously all the same. Just as the possession of nuclear weapons on both sides kept the Cold War cool, so the heavily-armed confrontation between NATO and Warsaw Pact forces was an effective deterrent. Ironically, after the demise of the Soviet imperium, NATO did find a role for itself in real shooting wars in the Balkans and Afghanistan. But when President Trump first arrived in the White House he made it clear he unsure the military alliance worth maintaining. His uneasy early meetings with European leaders in which his bluster won him no friends, appeared to confirm his belief that NATO should go. A particular bugbear for him was that the United States poured the largest amount of money and effort into keeping the alliance alive. Three years ago, only three member states met their treaty commitment to spend at least two percent of the GDP on their armed forces. Some governments, not least Angela Merkel's Germany, have since begun to up their military expenditure. However, the truth is that Trump was missing the real point. As the world's only superpower, America could simply not afford to withdraw from a NATO in which, from the start, it has played a dominant role. Washington's NATO allies might have welched on their financial obligations and sought to believe there was no longer any need to be heavily-armed against attack. A revisionist Russia and its aggression first in Georgia, then Ukraine and Syria has forced a review of European complacency. Trump may be right that NATO is no longer entirely fit for purpose, but it has nevertheless, rediscovered what that purpose is. The alliance's main problem at the moment is Turkey, supposedly a key member on its south eastern border. President Recep Tayyip Erdogan's increasingly eccentric geopolitical path, which includes close relations with Moscow and the purchase of a Russian missile system, is a direct challenge to the organization's basic cohesion. Even as Erdogan was sitting down for two days of talks in London at the NATO anniversary meeting, his soldiers were running their first proving tests of their new Russian S-400 anti-aircraft rocketry, missiles which are specifically designed to shoot down NATO's most advanced warplanes. Moreover, news was emerging that Ankara had signed a controversial deal with the UN-recognized government of Fayez Al-Serraj in Libya agreeing a maritime frontier in the eastern Mediterranean. This agreement completely disregards the offshore claims of NATO member Greece as well as Cyprus, Egypt, Israel and the Palestinians. NATO may understandably be starting to wonder if Turkey is less of an ally and potentially more of an enemy.