After twenty-three years of military occupation, intermittent warfare, and shifting geopolitical justifications, the United States has formally concluded its combat presence in Iraq. Officially marked on September 30th 2026, the final withdrawal concludes an era that began with the high-handed invasion of 2003. Yet, much like the abrupt departure from Afghanistan five years earlier, the exit leaves behind a fractured nation, anxious regional allies, and a glaring power vacuum that Iran and its network of local proxies are eager to fill.

The origins of Washington’s entanglement in Iraq are rooted in a mix of post-September 11th hubris and currency politics. When President George W. Bush issued a 48-hour ultimatum in March 2003 demanding that Saddam Hussein and his sons flee the country, the official casus belli was the threat of weapons of mass destruction (WMD). Beneath the surface of counter-terrorism rhetoric, however, lay an unsettling economic reality. Saddam had rattled Washington by attempting to trade Iraqi crude in euros rather than United States dollars. Since the early 1970s, when the Nixon administration struck a historic deal with Saudi Arabia to price global petroleum exclusively in dollars, the petrodollar standard had anchored American financial hegemony. Saddam’s challenge to this arrangement was an unforgivable transgression in the eyes of American strategists.

The military campaign itself was swift. Within weeks, Coalition forces swept through Baghdad; by December 2003, Saddam was captured in a subterranean hideout, later to be executed. But the strategic assumptions underlying the invasion proved spectacularly wrong. Bush’s promise that American troops would be greeted with flowers dissolved into an asymmetrical nightmare of sectarian bloodshed, insurgent attacks, and ideological radicalisation. The promised weapons of mass destruction were never found.

The timeline of American involvement underscores the sheer instability caused by the initial invasion:

Invasion and Fall of Saddam

March – December 2003

United States forces invade Iraq without United Nations backing. Baghdad falls within weeks, and Saddam Hussein is captured in December.

First Withdrawal Attempt

December 2011

American combat troops exit under President Barack Obama, leaving national security responsibilities to newly trained Iraqi security forces.

The Rise of ISIS and Re-intervention

2014

Taking advantage of the security vacuum, the Islamic State captures major cities including Mosul and Tikrit, forcing American forces to return.

The Formal Exit

September 2026

Washington officially declares an end to its military occupation, withdrawing remaining ground forces after twenty-three years of involvement.

The withdrawal of 2011 proved short-lived precisely because the destruction of the Ba'athist state had dismantled the institutional scaffolding of Iraq. In the chaos, radical groups flourished. The Islamic State of Iraq and Syria (ISIS) emerged as a far more formidable threat than Al-Qaeda, capturing vast swathes of territory across Iraq and Syria. Washington was forced to return in 2014 to lead a coalition against the jihadist caliphate. While ISIS was eventually stripped of its territorial footprint, its radical ideology remains potent, and local populations in former stronghold areas now fear a jihadist resurgence in the absence of Western deterrence.

The primary beneficiary of the American retreat, however, is not a Sunni extremist group, but Iraq’s eastern neighbour: Iran. Over two decades of occupation, Tehran meticulously cultivated an extensive network of Shia militias inside Iraq, organised under the umbrella of the Popular Mobilisation Forces (PMF). These groups have evolved into a formidable political and military force, targeting American bases and asserting influence over domestic policy. Even after American strikes killed Qasem Soleimani, commander of Iran’s Quds Force, alongside Iraqi militia leaders near Baghdad International Airport in 2020, the proxy network’s operational capacity remained intact.

Today, these Iranian-aligned forces operate with remarkable autonomy. Working alongside Houthi rebels in Yemen, Iraqi Shia militias have demonstrated their ability to disrupt key trade corridors, launching drone attacks against strategic infrastructure such as Saudi Arabia’s East-West pipeline. With American boots off the ground, Sunni political factions and the semi-autonomous Kurdish regional government in northern Iraq fear that Baghdad will fall entirely under Tehran’s sphere of influence, mirroring the structural dominance achieved by Hezbollah in Lebanon.

Washington insists that its strategic leverage over Iraq remains intact despite the military departure. American officials point to the tight financial leash held by the Federal Reserve Bank of New York, which safeguards roughly 80 to 85 billion dollars of Iraq's foreign reserves. Because petroleum exports account for nearly 90 per cent of Iraqi government revenues, and because oil transactions are cleared in dollars through New York, the Treasury Department retains the ability to starve Baghdad of liquidity. Indeed, Washington has already sanctioned over 35 of Iraq’s 72 commercial banks to curb illegal dollar flows to Iran.

Yet economic leverage is a blunt instrument when compared to armed presence on the ground. For regional capitals, the narrative of American exit is familiar and deeply alarming. From the chaotic withdrawal from Kabul to the recalibration of forces in Mesopotamia, Washington’s partners in Riyadh, Abu Dhabi, and Amman increasingly view American security guarantees as transient. The fear is that when local proxy forces press their advantage, Washington’s default response is not counter-escalation, but abandonment.

Looking across the primary objectives established at the outset of the intervention, the contrast between original ambitions and final outcomes highlights the magnitude of the shift:

When evaluated against the initial objective of eliminating weapons of mass destruction, the ultimate result after twenty-three years of occupation and inspections is that zero weapons were discovered, leaving the invasion's central pretext thoroughly discredited globally. Similarly, efforts to establish a stable democratic model yielded a fragmented sectarian state, where effective power has steadily shifted toward armed proxy groups like the Popular Mobilisation Forces (PMF).

On the regional front, Washington's attempt to contain Iranian influence backfired entirely: Tehran now commands a dominant sway across Mesopotamia, backed by an active militia network operating from Baghdad to the Red Sea. While the United States retains indirect economic control as a mechanism for financial leverage holding 80 to 85 billion dollars of Iraqi reserves in the New York Fed and sanctioning 35 of Iraq's 72 commercial banks this leverage is constrained by Iraq's extreme oil revenue dependence, where 90 per cent of the national budget is derived from dollar-cleared petroleum sales.

As celebratory rallies take place among Shia militia groups in Baghdad, the broader Middle East absorbs the reality of a shifted balance of power. After trillions of dollars spent, thousands of military personnel lost, and hundreds of thousands of Iraqi lives ended, the United States leaves behind a country far closer to Tehran than to Washington. Financial controls may offer the Treasury Department a degree of indirect pressure, but on the streets of Baghdad, Mosul, and Erbil, the political reality is inescapable: the era of American occupation is over, and the era of Iranian primacy has begun.