Iran Sanctions Squeeze Tests Dollar's Role as Oil Weapon

The United States dollar's long dominance as the instrument of economic coercion is facing one of its most sustained tests yet, as Washington's renewed sanctions campaign against Iran collides with a quietly expanding network of alternative payment corridors, barter arrangements, and third-country intermediaries that Tehran has spent years constructing. The squeeze is real — but so are its limits.

American officials have repeatedly described the sanctions architecture as a decisive lever capable of forcing behavioural change in Tehran. Yet data compiled by independent analysts and flagged in reports by the UN Panel of Experts indicate that Iranian crude exports have continued flowing to Asian markets, primarily China, at volumes that undercut the headline narrative of a hermetically sealed embargo. The gap between the policy's ambition and its operational reach has become one of the defining fault lines in contemporary geopolitical economics. (Source: Reuters, UN Panel of Experts)

Maximum Pressure, Minimum Compliance

The doctrine of maximum pressure rests on a straightforward premise: deny Iran the dollar-clearing access it needs to sell oil, and the regime must either capitulate or collapse. The logic held reasonable sway in earlier sanction cycles, when Iranian banks were expelled from the SWIFT interbank messaging system and international insurers withdrew cover from tankers carrying Iranian cargo. Those measures caused demonstrable economic pain, according to International Monetary Fund assessments cited by Reuters.

The SWIFT Exclusion and Its Unintended Consequences

Removing Iran from SWIFT did serious damage to its formal banking sector. But it simultaneously accelerated the development of parallel clearing mechanisms — informal hawala networks, bilateral currency swap agreements with willing partners, and cryptocurrency channels that regulators in multiple jurisdictions are still scrambling to map. Officials at the Financial Action Task Force have publicly acknowledged that the sanctioned-entity ecosystem has grown in sophistication precisely because exclusion from formal rails forced innovation. The irony is not lost on Western treasury officials, several of whom have privately conceded to Financial Times reporters that the pressure generated adaptive capacity it was intended to destroy. (Source: Reuters, Financial Times)

Questions about the coherence of the US-led sanctions coalition have also acquired a sharper legislative dimension in Washington. As House divisions over Iran policy test Republican unity behind the Trump agenda, the administration faces pressure from multiple directions simultaneously — hawks demanding tougher enforcement and a sceptical cross-party bloc questioning the absence of a diplomatic off-ramp.

Oil Flows Through the Shadows

Iran's export statistics are, by design, opaque. Tehran ceased publishing granular production data years ago, and third-party tracking relies on satellite imagery of tanker movements, port activity data, and shipping registry analysis. The picture that emerges from aggregated intelligence, cited by AP and corroborated by tanker-tracking firms including Kpler and Vortexa, is one of persistent, if fluctuating, export volumes to Chinese independent refineries — the so-called "teapots" — that have shown little appetite for compliance with US secondary sanctions.

China as the Structural Anchor

China's role is not incidental. Beijing has absorbed the majority of Iran's sanctioned crude through a network of smaller, privately held refineries that are largely beyond the reach of US secondary sanctions enforcement because they maintain minimal dollar exposure and no meaningful US banking relationships. Payment occurs in Chinese yuan, in commodity offsets, or through intermediary accounts held in Gulf financial centres and Southeast Asian jurisdictions with lighter regulatory footprints. According to shipping data compiled by Reuters, Iranian exports to China have at times reached levels comparable to those recorded before maximum pressure measures were first imposed.

The broader pattern of sanctions circumvention through commodity-backed bilateral deals is not unique to the Iran case. Analysts tracking the Western Hemisphere have noted comparable dynamics at play as a Venezuela energy arrangement tests the structural durability of the US sanctions architecture — a parallel that policymakers in Brussels and London are following with considerable unease.

Ghost Fleets and Flag-Hopping

The physical logistics of Iranian oil exports have evolved into a specialist discipline. A significant portion of Iranian crude travels aboard a fleet of ageing tankers that routinely disable their Automatic Identification System transponders, transfer cargo at sea via ship-to-ship operations, and re-flag under obscure registries in jurisdictions that do not cooperate with US enforcement requests. The UN Panel of Experts on Iran documented dozens of such transfers in its most recent published report, noting that the vessels involved frequently used falsified certificates of origin to rebrand Iranian crude as cargo from legitimate third-country producers. (Source: UN Panel of Experts, AP)

The Dollar's Structural Advantage — and Its Erosion

The dollar remains, by a commanding margin, the world's dominant reserve currency and the standard denomination for global oil trade. This structural reality is what gives US sanctions their coercive edge: any bank, anywhere in the world, that processes dollar transactions is subject to US jurisdiction, creating a powerful enforcement mechanism that reaches far beyond American borders. It is this extraterritorial reach, rather than any bilateral trade relationship, that makes Washington's financial toolkit genuinely formidable.

De-Dollarisation as a Long-Term Project

But the dollar's centrality is no longer treated as immutable by an increasing number of state and non-state actors. Russia's expulsion from SWIFT following its invasion of Ukraine accelerated discussions within the BRICS grouping — which now includes Iran as a full member — about developing alternative settlement mechanisms. While a functional, scalable BRICS payment system remains a distant prospect, the direction of travel has shifted measurably, according to analysis published in Foreign Policy. The accumulation of small workarounds — yuan invoicing, bilateral barter, digital currency pilots — does not individually threaten the dollar's primacy, but in aggregate represents a structural chipping at the foundations that US Treasury officials have begun to treat with greater seriousness. (Source: Foreign Policy, Reuters)

The geopolitical stakes of that erosion extend well beyond Iran. If sanctioned states can demonstrate that the costs of dollar exclusion are manageable, the deterrent value of financial pressure diminishes across every future crisis in which Washington might seek to deploy it.

European Exposure and the UK Dimension

For the United Kingdom and European Union member states, the Iranian sanctions question operates on at least two distinct registers: security and economic. On the security side, continued Iranian oil revenues — however diminished — sustain a defence industrial base, proxy militia networks, and ballistic missile programme that European intelligence agencies assess as direct threats to regional stability and, by extension, to European interests in the Middle East. (Source: AP)

European governments have moved to tighten their own sanctions frameworks in response. Discussions in Brussels about reinforcing the restrictive measures regime have intensified, with member states debating whether existing tools are adequately calibrated to address financial intermediaries and shipping service providers that facilitate Iranian exports indirectly. Readers following those deliberations can find detailed coverage in our reporting on how the European Union is weighing stricter sanctions tied to Iran's nuclear programme, as well as the more recent measures documented in our analysis of how the EU has moved to tighten Iran sanctions in response to nuclear advances.

For Britain specifically, the picture carries an additional layer of complexity. Post-Brexit, the UK maintains its own sanctions regime — broadly aligned with the EU but no longer automatically synchronised. British officials at the Office of Financial Sanctions Implementation have signalled a desire to maintain substantive coordination with European counterparts, but the mechanisms for doing so are less institutionally embedded than they were during the pre-Brexit period. London's role as a global financial centre also creates exposure: the City remains a node through which sanctioned-entity beneficial ownership structures have historically been obscured, a vulnerability that the government's economic crime legislation is only partially addressing. (Source: Reuters, Financial Times)

Military Dimensions and Diplomatic Paralysis

The sanctions campaign does not exist in a vacuum. Economic pressure has historically been paired with, or supplanted by, military signalling — and the Iranian theatre has seen both. The continuing pattern of kinetic incidents involving Iranian-backed forces in Iraq, examined in detail in our coverage of how an Iranian strike on US troops tested rules of engagement in Iraq, illustrates the degree to which economic and military pressure vectors interact and at times undermine one another.

Diplomatic channels, meanwhile, remain effectively frozen. There is no active multilateral negotiation framework capable of converting economic pain into binding behavioural commitments, and Tehran has repeatedly signalled that it regards the current pressure campaign as an instrument of regime change rather than a sincere attempt at negotiated constraint. That perception — accurate or not — reduces the probability that even significantly intensified economic pressure will produce the concessions Washington seeks. (Source: Foreign Policy, AP)

What Happens Next

The near-term trajectory of the sanctions campaign will be shaped by enforcement willingness rather than legal authority — Washington already possesses sweeping statutory powers to punish secondary violators, but has exercised them selectively to avoid triggering retaliatory economic measures from Beijing. That political calculus is unlikely to change dramatically in the short term, leaving the sanctions regime in its current state of partial effectiveness: painful enough to constrain Iran's fiscal options and limit its access to imported technology, but insufficient to stop crude from moving or to force a strategic recalculation in Tehran.

For European and British policymakers, the lesson being absorbed is an uncomfortable one: the dollar-based sanctions system, while still the most powerful economic coercion instrument available to the Western alliance, is no longer as close to absolute as it once appeared. Designing future pressure campaigns will require confronting that reality honestly — and investing, well in advance, in the enforcement infrastructure and diplomatic coalition-building that transforms legal authority into actual leverage. The alternative is a tool that signals resolve but delivers increasingly diminishing returns.