Since the end of the Second World War, NATO has played a crucial role in defending western countries and the liberal democracy against the threat of the Soviet Union. However, the world has changed, and so has NATO. Especially after the end of the Cold War, NATO lost its utmost enemy and, at the same time, its raison d’etre. Ironically, however, since then, the threats surrounding the alliance have exponentially increased. These include regional conflicts, terrorism, cyber-attacks, hybrid wars, and other challenges. In this circumstance, the inner cacophony among member countries has also been dramatically magnified. The peak was a controversial debate concerning burden-sharing in the defense budget, which was the central theme in the Trump era. Moreover, Turkey’s introduction of a Russian missile system and French President Macron’s provocative remark, “NATO is brain-dead”: all these situations worsened the alliance’s image and the relations among its members. However, these criticisms have seemingly become muted since the onset of the Biden administration. Meanwhile, have these problems really been solved? What were the true reasons for these dissonances? Does NATO have any plan to overcome all this noise? Furthermore, what could be the lessons of NATO’s case for other military alliances?