The US-led international order has long rested on three interconnected pillars: political legitimacy, economic stability and military power. Since the early 2000s, however, each has been increasingly weakened. The invasions of Afghanistan and Iraq, the global financial crisis and the Trump presidencies ruptured the first two. The US’s apparent impotence in the current conflict with Iran now appears to be breaking the last.

Fracturing foundations

Since the early 2000s, several crises have weakened the liberal international order. The first followed the terrorist attacks of September 11, 2001, and the subsequent US invasions of Afghanistan and Iraq. The prolonged occupations, widespread instability, and extensive loss of life diminished the perceived legitimacy of overwhelming military force as a tool of geopolitics. Reports of torture, particularly at Abu Ghraib, along with secret prisons, extraordinary rendition and limited political reforms, further damaged the credibility of the military, social and political foundations of the US-created order.

One of the infamous photos from the US-run Abu Ghraib prison in Baghdad during the American invasion of Iraq in 2003; the image of a hooded Iraqi inmate apparently being tortured caused widespread revulsion and outrage, particularly in the Muslim world.

In turn, the 2008 credit crisis generated a comparable crisis of confidence in the economic foundations of this order. Originating in the US subprime banking sector, the crisis questioned both the stability of the global financial system and the wider logic of US-led neoliberal economic governance. The apparent failure of financial institutions to regulate themselves, combined with the social consequences of the crisis, also weakened faith in the universal benefits of the liberal economic model.

During Donald Trump’s second presidency, further actions have accelerated this decline, including withdrawal from, or rejection of, key multilateral institutions, including the United Nations Human Rights Council, the World Health Organisation and Unesco. Tensions within Nato concerning Russia’s invasion of Ukraine have unsettled longstanding alliances, while expansion of the US nuclear arsenal has undercut non-proliferation efforts.Trump’s authoritarian tendencies, and his encouragement of similar leaders abroad, have also weakened democratic norms. Such actions have debased the central premises of this international order.

An addiction to military power

Military force has long been central to US foreign policy. The 1823 Monroe Doctrine asserted American hegemony over the Western Hemisphere. Then in 1947, President Harry Truman presented US leadership as essential to defending freedom and preserving world peace. In turn, the 1950 NSC-68 document called for covert economic, political and psychological operations to support unrest in strategically important states. Later, the 1957 Eisenhower Doctrine authorised military action in the Middle East, while the 2002 National Security Strategy formalised a doctrine of preventive war.

Via 400 military interventions since 1776, the US has often used force to participate in numerous regime-change operations. Some targeted democratic governments and replaced them with authoritarian regimes, particularly in Central and South America during the Cold War. Others helped to acquire territory and expand regional influence in places such as Mexico, Samoa, Hawaii and Panama. Further afield, interventions in countries including Iran, Cuba, Guatemala, Korea, Vietnam and Iraq pursued strategic and economic goals, including access to oil, gas, fruit, sugar, markets and trade routes.

Militant Pakistani religious activists have a stark message for the US during a rally in Islamabad, in the immediate aftermath of the September 11, 2001 terrorist attacks on America.Photo: B.K. Bangash / AP

Intervention was repeatedly justified as necessary to protect democracy and human rights. At the same time, US alliances, military bases and arms sales enabled Washington to project power globally. In 2025, around 222,000 US military and civilian personnel were stationed in more than 175 locations abroad across 750-800 military bases in 80 countries.

Average annual US military spending rose from approximately US$336 billion in the 1990s to US$688 billion in the 2010s. In 2025, this figure reached US$954 billion, more than a third of the global total. In mid-2026, President Trump requested that the budget further rise to US$1.5 trillion in 2027. Over the last 75 years, the US also sold US$767 billion worth of weapons, 36% of the global total. From 1945, US military campaigns are estimated to have caused between 4m and 9m military and civilian deaths worldwide.

The Iran inflection point

In the last six months, the ongoing US-Israel conflict with Iran has shown the limits of US military power. Facing the asymmetric threat of Iranian drones, which at US$20,000 each, cost a fraction of the US$4 million price of US interceptor missiles, the US has been unable to gain primacy in the conflict. This includes being unable to control the Strait of Hormuz and the depletion of US weapons stockpiles, including those from East Asia and Europe.

Since the beginning of the conflict, Tehran’s strikes have also damaged US military installations, disrupting its command networks and degrading its missile defence systems. A retired four-star general subsequently declared that the US has “ probably permanently lost access to 15 Persian Gulf bases”. Such damage has reduced the US’s power projection capabilities and its ability to guarantee security to regional allies. The ineffectiveness of US military power is underlined by having no feasible exit from the war.

The final American evacuees are flown from the US embassy in Saigon after the North Vietnamese victory in the Vietnam War, in April 1975. While it was more protracted and bloody than most of America’s military adventures, the war was one of more than 400 military interventions by the US since 1776, writes Chris Ogden.Photo: AP

The British historian Arnold Toynbee noted how declining empires often resort to military adventurism. We can see this in the US’s 21st century forays into Afghanistan, Iraq, Syria, Libya and now Iran. The incoherence of US foreign policy, growing distrust and weakness in its alliance system, and a spiralling US military budget point to deep seated inertia amongst its leaders, which appears to be dynamiting the last remaining pillar of US power.

The denouement of the Western-led international order will herald a world transitioning to a more Asia-centric and multipolar system. This transition will see greater competition between the US and China, but also the creation of new interactions, particularly within the Indo-Pacific. Such a world will present challenges and opportunities for all countries, including New Zealand, which will need dynamic, creative and nimble leaders to thrive.