The Limitations of US Pressure on Iran over the Decades

Spotlight

• The US policy towards Iran has shifted from engagement to maximum pressure and military confrontation, but each approach has struggled to deliver lasting strategic change.
• Despite severe economic and military costs, Iran has adapted to the external pressure while maintaining its core security and regional policies.
• The central challenge for Washington is to see whether a sustained blockade and military strikes can change Tehran’s calculations without creating an open-ended conflict that becomes increasingly costly to maintain.

Over the past two decades, the United States (US) has tested three main approaches towards the Islamic Republic of Iran, each based on a different assumption about how Tehran could be influenced.

The first approach (2009–16) combined engagement with economic pressure, based on the belief that sanctions could strengthen pragmatic forces inside the Islamic Republic and create conditions for diplomatic compromise. The second phase (2008–September 2023) consisted of maximum pressure and deterrence. The third phase (October 2023–present day) emerged after rising regional tensions following the 7 October 2023 attacks on Israel and the wider escalation involving Iran and its regional partners. This last phase has been defined by increased military confrontation and attempts to weaken the Islamic Republic’s strategic capabilities.

Despite severe economic and military costs, Iran has adapted to the external pressure while maintaining its core security and regional policies.

However, none of these strategies achieved its broader objectives. The first led to a nuclear agreement but failed to transform US–Iran relations. The second damaged the Islamic Republic’s economy but did not change Tehran’s strategic behaviour. Military escalation has demonstrated the US’s ability to strike Islamic Republic capabilities but failed to lead to any change. The future of US policy towards the Islamic Republic, therefore, depends on developing a strategy that avoids repeating the limitations of the previous approaches.

Phase One: Engagement and Economic Pressure (2009–2016)

When Barack Obama entered the White House in 2009, many policymakers believed that a diplomatic opening with the Islamic Republic could be possible. Unlike previous administrations, Obama’s attempted to combine direct engagement with economic pressure. His Nowruz message to the Islamic Republic’s leadership and population signalled that Washington was willing to move beyond decades of hostility if Tehran was prepared to pursue a different relationship.

However, this engagement was accompanied by increasing sanctions. Following the disputed June 2009 presidential election in Iran and the Green Movement protests, tensions between Tehran and Washington increased. From 2011 onwards, the Obama administration expanded sanctions targeting the Islamic Republic’s financial sector, oil exports, and access to international markets. These measures were further intensified throughout his presidency, particularly through restrictions on the Islamic Republic’s banking system and energy sector.

The purpose of the sanctions was not only economic punishment; they aimed to create sufficient pressure on Tehran to encourage negotiations while simultaneously strengthening moderate political forces in the Islamic Republic that supported engagement with the international community.

Military escalation has demonstrated the US’s ability to strike Islamic Republic capabilities but failed to lead to any change.

This approach eventually led to the Joint Comprehensive Plan of Action (JCPOA), signed in July 2015. Under the agreement, the Islamic Republic accepted major restrictions on its nuclear programme. Uranium enrichment was limited to 3.67 percent, the number of operating centrifuges was reduced, and Iran’s enriched uranium stockpile was significantly decreased. In return, nuclear-related international sanctions imposed by the United Nations (UN) and the European Union (EU), as well as US secondary sections, were lifted. The JCPOA also created a new set of expectations within the Islamic Republic. President Hassan Rouhani and Foreign Minister Javad Zarif viewed it as the first step towards improving relations with the western community. In contrast, Supreme Leader Ayatollah Ali Khamenei rejected the idea that the agreement represented cooperation on a wider front with Washington, maintaining that negotiations were limited exclusively to the nuclear issue.

This difference became a major limitation. While supporters of engagement hoped that the agreement could open the door to broader diplomatic progress, Iran’s leadership continued to view the US as a strategic adversary.

The election of Donald Trump as US president in 2016 marked an important change in direction of US–Iran relations. The JCPOA remained active when Trump entered office, but tensions continued over issues beyond the nuclear deal, including the Islamic Republic’s missile programme, regional activities, and financial restrictions imposed upon it.

A decisive shift took place in May 2018, when the US withdrew from the JCPOA and restored its earlier secondary sanctions targeting Iran’s oil exports, banking access, and international trade, although the international and European sanctions lifted under the agreement were not immediately reinstated. This greatly reduced the economic benefits the Islamic Republic had expected from the agreement.

Phase Two: Maximum Pressure and Deterrence (2018–October 2023)

Following its withdrawal from the JCPOA, the US adopted a “maximum pressure” strategy. The objective shifted from encouraging internal moderation through economic incentives to imposing costs on Tehran’s nuclear and regional policies through means other than sanctions.

However, Tehran adapted by expanding its domestic defence production, strengthening ties with non-Western partners, and gradually reducing its commitments under the JCPOA.

The economic impact was strong. Inflation increased, foreign investment declined, and access to international financial markets became more restricted. Yet, these pressures did not weaken the institutions responsible for the Islamic Republic’s security strategy. The Islamic Revolutionary Guard Corps (IRGC) remained central to Iran’s domestic and regional policies, while it continued to support allied groups across the Middle East, including Hezbollah in Lebanon, armed groups in Iraq and Syria, and the Houthis in Yemen.

The nuclear issue also moved in the opposite direction. Following the US withdrawal from the JCPOA, the Islamic Republic gradually crossed the limits imposed by the agreement, expanding enrichment activities, increasing its uranium stockpile, and developing advanced centrifuge capabilities.

Economic pressure, meanwhile, could severely weaken the Iranian economy without necessarily forcing political change.

The Biden administration attempted to revive negotiakeytions with Iran after taking office in 2021, but the political environment had changed. The Islamic Republic’s conservative establishment had strengthened following the election of Ebrahim Raisi, while mistrust between the two nations had deepened.

The “maximum pressure” approach demonstrated that the US could impose substantial economic costs on Iran. However, it failed to fundamentally change Tehran’s strategic calculations. It succeeded as a punitive measure but failed as a strategy of transformation.

Phase Three: Military Escalation and Strategic Confrontation (October 2023–Present)

The 7 October attacks and subsequent war on Gaza marked a shift in US policy, as Washington moved from diplomacy and economic pressure towards directly confronting the Islamic Republic’s regional network and military capabilities.

The focus expanded beyond Iran’s nuclear programme towards weakening the broader strategic infrastructure that supported its influence. The US increased military deployments, strengthened support for Israel, and focused on the Islamic Republic’s missile capabilities, drone production, and regional partners.

This approach was not initially designed around regime change. Instead, the objective was to reduce Iran’s ability to threaten US allies, its regional security, and critical infrastructure.

However, escalating confrontation increased concerns regarding the Islamic Republic’s nuclear trajectory and long-term strategic intentions. Iran’s continued activities, including uranium enrichment up to 60 percent, heightened fears that Tehran could move closer to nuclear weapons capability, although it continues to deny pursuing nuclear weapons.

The escalation eventually developed into direct military confrontation in June 2025. The 12-day war between Iran, Israel, and the US demonstrated both Islamic Republic resilience and vulnerability.

Economic pressure, military setbacks, and domestic unrest exposed growing vulnerabilities, but did not lead to a fundamental strategic shift. Conservative elements remained dominant, and the Iranian leadership continued to prioritise resistance. Iran also continued to use regional pressure points, including maritime routes and strategic waterways, as part of its deterrence strategy.

Phase Four: The Search for a Sustainable Strategy

The current situation since February 2026 raises the question of whether the combination of military and economic pressure is beginning to have a different effect. The US naval blockade has created pressure that sanctions alone struggled to achieve by restricting Iran’s ability to export oil and earn foreign currency. At the same time, the announcement of new sanctions is intended to further isolate Iran from international trade and financial networks.

The pressure is increasingly visible on an already weakened Iranian economy. It has led to continued deterioration of the rial, alongside high inflation, disrupted trade, and declining oil revenues.

However, whether this can break the Islamic Republic’s resolve depends not only on the campaign’s intensity but also on its longevity. A short period of extreme military and economic pressure may inflict high damage, but without fundamentally changing Tehran’s calculations if its leaders believe they can outlast the situation.

Conversely, a sustained combination of a naval blockade, expanding sanctions, and military pressure could gradually weaken Iran’s ability to finance the state, sustain military operations, and absorb the costs of continued confrontation. Yet, sustaining such a campaign would also impose political, military, and economic costs on the US and its partners.

Military escalation presents a similar dilemma. Further strikes could weaken Iranian military capabilities, but they could also encourage retaliation rather than surrender. Economic pressure, meanwhile, could severely weaken the Iranian economy without necessarily forcing political change.

The key question therefore is whether the US–Israel campaign can be intense enough to change Tehran’s calculations and sustainable enough to outlast the Islamic Republic’s willingness and ability to resist and wait.

Additionally, Iran might be betting on its ability to outlast the current campaign until the US midterm elections and Israel’s next election. A shift in political dynamics in Washington could constrain

Trump’s ability to sustain funding and domestic support for the war, while political changes in Israel could reduce Netanyahu’s room for manoeuvre. This could eventually create openings for negotiations on more favourable terms for Tehran, giving it greater leverage at the negotiating table.

The key question therefore is whether the US–Israel campaign can be intense enough to change Tehran’s calculations and sustainable enough to outlast the Islamic Republic’s willingness and ability to resist and wait.

Kamyar Kayvanfar is a native Persian and English-speaking communications and public affairs professional with experience at EY and KREAB.