The North Atlantic Treaty Organization (NATO) was formed in 1949 as a repudiation of the geopolitical brinkmanship that birthed two catastrophic world wars.

The charter of NATO was premised on a system of collective security in which member states pledge to defend one another in order to deter aggression or to target a transgressor if international order has been breached. It is not possible to decode contemporary diplomacy without first understanding the systemic effects of that collective security framework.

Collective security schemes have a storied history. In 1629, Cardinal Richelieu proposed a collective defense structure for Europe that was at least partially implemented in 1648 by a pair of treaties that ushered in the Peace of Westphalia.

In the 18th century, Enlightenment philosophers lobbied for similar concepts. Immanuel Kant’s 1795 tome, Perpetual Peace: A Philosophical Sketch, suggested a “league of nations” would be an efficient way to control conflict and promote peace between states.

In the 19th century collectivist diplomacy was implemented through an informal process known as the Concert of Europe, which safeguarded the territorial boundaries of Great Power states (Austria, France, Prussia, Russia, and the UK) and was generally successful in localizing military conflict.

In 1889, peace activists formed the Inter-Parliamentary Union to encourage governments to solve international disputes by peaceful means and arbitration. But the effectiveness of this Union was undermined as the Great Powers sorted themselves into opposing treaty blocs.

Like NATO, those alliances committed the major European states to support their partners diplomatically and militarily. The assassination of Archduke Ferdinand of Austria by Bosnian separatists ultimately triggered a spiral of treaty-fueled diplomatic escalation that culminated in WWI, killing an estimated 9 million soldiers and 5 million civilians.

The carnage of WWI provoked the formation of the League of Nations in 1920. The charter of the League was principally focused on avoiding industrial scale war. It created a framework for negotiation and arbitration to resolve disputes, and advocated for disarmament and collective security agreements.

The League of Nations failed to achieve its goals, and it failed primarily for structural reasons.

While ostensibly a community of sovereign peers, the permanent membership of the League’s Executive Council was comprised solely of the victorious WWI allies (Britain, France, Italy, Japan).

As with the Treaty of Versailles, this “winners rule” structure was famously responsible for much of the reactionary populism that powered Hitler’s political ascent and Germany’s eventual rearmament.

The Executive Council states were also tasked with enforcing the League’s resolutions and economic sanctions, and providing forces to execute military actions as needed. They embraced those responsibilities reluctantly at best, often pulling punches to avoid economic or diplomatic friction.

League credibility also suffered from incomplete representation. Membership peaked at 58 member states. Despite the advocacy of President Woodrow Wilson, the United States never joined. The Soviet Union joined late and was expelled shortly thereafter for invading Finland.

The League’s failures culminated with the onset of WWII in 1939. After the war, the United Nations (UN) was salvaged from the carcass of the League.

The UN charter attempts to address the League’s shortcomings. Adversaries are represented on the Security Council, and rotating membership is traded among lesser powers. Started with 51 states, the UN also expanded representation dramatically, reaching 193 members in 2011.

Like the League, the UN does not maintain its own military, relying instead on members to volunteer resources to peacekeeping missions. Where the UN provides the legal and diplomatic infrastructure of the post-WWII order, NATO has largely determined the security dynamics and alignment of military resources.

One of the foundational truths about NATO is that the US pledged to provide the dominant portion of the alliance’s military resources in order to avoid another European arms race. In effect, the US signed up to be the policeman of Europe and the Middle East in order to diminish another repeat of the spiraling competition that caused two world wars.

This “over commitment” of US forces has increasingly drawn criticism over time. Donald Trump famously called the virtues of NATO into question during his tenure as President, and shamed our allies for not meeting their collective pledge to spend 2% of national GDP on security. The combined military spending of all NATO members in 2020 constituted over 57% of all global defense spending.

NATO’s core mission has never been questioned so publicly before, and its expansion, from 12 founders to an alliance of 30, has also evolved into a flashpoint.

The notion of US troops aiding autocrats like Recep Tayyip Erdogan of Turkey is politically and morally repugnant. NATO expansion among former Soviet satellites animates Vladimir Putin’s current diplomatic machinations. And NATO’s effectiveness in countering China’s growing ambitions is also open to question.

NATO and the UN have mostly succeeded in promoting global stability since 1949. Can they continue to do so in the dynamic times ahead?