But then came the terrorist attack on September 11, 2001, known as 9/11, which was orchestrated by Al-Qaeda, led by Osama bin Laden, and killed almost 3,000 people.

The attack resulted in the famous declaration of a global war on terror that saw invasions of Afghanistan and Iraq, as well as massive investment in American military and intelligence infrastructure in the Middle East and parts of North Africa.

Successive American presidents attempted to pivot away from the region, but found themselves drawn back into perpetual wars that lasted almost two decades in some cases.

The withdrawal of American forces from Afghanistan in 2021 appeared to bring that chapter of America’s military history to a close, with a mixed though not entirely unsuccessful legacy. 

However, it is arguable that President Trump’s war with Iran is the dying breath of the 9/11 chapter of America’s military engagements. 

America’s Military Might

America has long been proud of its army. Memorials to veterans are common in many towns, as is the perhaps curious practice of naming rest areas along highways after military personnel.

Veterans are commonly given preferential treatment in insurance, mortgages and so on, while it is not uncommon for the average American to come up to serving military personnel in a shop to thank them for their service.

Aside from the respect shown to the troops themselves, America’s military might has been largely taken for granted at least since World War II. 

America has never lost a war against a foreign actor on its own soil – a fact sometimes deployed to explain its bullish approach to wars abroad – and played a decisive role in the two major conflicts of the 20th century.

Equally, although its best-remembered military involvements in the Cold War are arguably the stalemate in Korea and defeat in Vietnam, it successfully projected an image of military might that was sufficient to defeat the Soviet Union.

However, with the collapse of the USSR and the communist threat, there was a resurgence in a certain skepticism among the American public as to the necessity – or at least the extent – of the country’s interventionist approach.

It is worth recalling that there was strong opposition at home to its involvement in both the world wars, while its misadventure in Vietnam had somewhat soured the image of America as the defender of global freedoms.

Meanwhile, with communism defeated, there was no obvious enemy on the horizon – polls prior to 9/11 suggested that Americans viewed China as the most significant threat, but not one worth military engagement. 

Moreover, Roger Cliff, a Pentagon official at the time of 9/11, argues that the 1991 Persian Gulf War, which lasted only six months, had demonstrated the ability of the United States to “easily eviscerate the conventional forces of any regional power that might think to threaten US interests”.

It is hardly surprising, in this light, that Bush and Gore would take a nuanced approach to foreign policy and military engagement, as described above. There appeared to be no urgency – America was incontestably the world’s only superpower and could now focus on domestic affairs.

War on Terror

But public and political attitudes to war would change considerably following 9/11. A new enemy came into view, a dangerous and nebulous collection of Islamist terror groups that had inflicted the deadliest terrorist attack on American soil.

Immediately, Bush went on the offensive, declaring a war on terror that would come to justify military engagements not only in Afghanistan – home to bin Laden – but also in Iraq, Iran, Yemen, Syria, Libya and more.

On 14 September, Congress passed the Authorization for Use of Military Force, a joint resolution granting broad powers to the US president to use force against those responsible for the attacks, and there was little hesitation in deploying troops.

Public support for Bush was overwhelming – his approval ratings soared to 90% – while America’s allies were quick to join it in its military campaign in Afghanistan, which sought to take down Al-Qaeda on its own turf, beginning in October 2001.

Defeating terrorism, especially of the Islamist variety, became the new goal of America’s defense policy, having been merely one consideration among many just months before.

Almost as important, having been hit badly on its own soil, America was emboldened once again to see its mission as leading the fight for freedom and justice in the world.

The name of its Afghanistan campaign, Operation Enduring Freedom, left no one in any doubt about the nation’s view of its wars.

Republican presidential candidate John McCain summed up his views succinctly during his failed 2008 campaign, stating: “We don’t hide from history. We make history.”

Middle East Expansion

America had been significantly involved in the Middle East for decades prior to 9/11, with roughly 27,000 troops in situ at the time of the attacks. 

However, with the overwhelming support of the public, Bush rapidly started to expand America’s military presence, increasing the number of bases and pouring in troops; at the height of the war, there were around 250,000 US military personnel in the Middle East.

As with Afghanistan, the terrorist threat was used to justify invading Iraq to overthrow Saddam Hussein in 2003, a war now remembered for false assertions that Hussein had amassed weapons of mass destruction. 

Although the Iraq War soured the US relationship with many of its allies, countries like Britain and Poland continued to support America’s mission. With troops and US bases proliferating in the region, it was a show of force and a projection of power that had proven successful in the Cold War. 

When President Bush effectively declared victory in Iraq in May 2003 with his “Mission Accomplished” speech, it seemed as though the US was an unstoppable force and the second Iraq War was a rinse-and-repeat of the Persian Gulf War, in which a six-week air campaign was followed by a short, decisive ground assault.

Ending Forever Wars

However, Bush’s celebration proved premature. It was not until eight years later that then-President Barack Obama would wind down the American presence in Iraq – although he was forced to send US forces back in 2014 as the Islamic State (IS) became a major force.

And it was not until 2021 that America would pull out of Afghanistan, under a plan drawn up by Trump and carried out by Joe Biden.

After Bush’s re-election in 2004, all the subsequent successful presidential candidates – Obama, Trump, Biden and Trump again – expressed a desire to extricate the US from unpopular forever wars. Biden and Trump in particular argued against further attempts to remake foreign countries through military action.

The US had achieved its major aim of reducing the terrorist threat on its shores – there was no repeat of 9/11, while Roger Cliff calculated that the average annual number of people killed in terrorist attacks in the US, excluding the 9/11 victims, fell by roughly half from the 1975–2001 period to the 2002–2020 period.

However, mounting military casualties, images of abuse carried out by US soldiers and an economic recession at home undermined public support.

As the wars dragged on, so many American government officials promised to “pivot” out of the region, only to be sucked back in, that the phrase became a running joke in defense circles.

Declining American Prestige

In 2024, Donald Trump ran on a campaign pledge to end US engagement in foreign wars, such as the Ukraine-Russia conflict, and a promise to put America first. While his promises echoed Bush’s in 2000, there were key differences. 

Bush rejected isolationism, arguing that it “abandons our allies and our ideals” and would produce “a stagnant America and a savage world”, but Trump has largely embraced this policy.

Equally, while Bush was dealing with a country bristling with self-confidence during a period of material prosperity, Trump was appealing to a nation that had taken too many knocks abroad and was still struggling to overcome economic stagnation after Covid-19.

It appeared that, after the withdrawal from Afghanistan and Trump’s re-election, the post-9/11 chapter in US history was drawing to a close. 

However, Trump’s decision to launch military operations against Iran earlier this year is arguably its dying breath.

The justifications for engagement mirrored those for Afghanistan and Iraq: the perceived threat of nuclear weapons in the hands of a hostile power, a belief that the war could be ended quickly with an overwhelming show of force and proposals for regime change.

Just as the justifications mirror those of the wars following on from 9/11, so too does the struggle to overcome an enemy whose resolve and resources are deeper than America predicted. Even the absence of any real consideration of putting boots on the ground is a hangover from the prolonged conflicts in Afghanistan and Iraq.

Perhaps most significantly of all, however, are the attacks launched against the symbols of American might, the projection of its military power – its bases. This is as close as the great nation of the West has come to seeing its overseas military infrastructure directly attacked on such a scale.

America Turns Inward

Now, with 50,000 military and intelligence personnel still in the Middle East, there is talk that America will wind down its presence once the Iran war comes to a close.

At the same time, regional powers have begun to establish military pacts of their own, as it appears the age of relying on the US is ending. 

The same story is playing out in Southeast Asia and in Europe, where allies are scrambling around in a bid to adjust to America’s changing priorities.

In a sense, the signs are that the American public and politicians are returning to the pre-9/11 status quo, their gaze turning inward, their appetite for war diminishing.

The legacy of these policies remains a source of hot debate. While they proved successful in protecting America, they produced destabilization through a series of regime changes, and the continued existence of both Al-Qaeda and IS meant key terrorist networks remained undefeated.

But there seems to be a perception now that losing is a possibility and that the US is not only a history maker but, as Martin Luther King Jr put it, made by history – and subject to it.

That need not be the end of America’s efforts to shape the world in the name of goodness and justice, but if it tries again, it may be with the kind of scars that toughen a soldier, but also make him wary of excessive zeal for combat.