Between 2017 and 2021, the United States under President Donald Trump pursued a confrontational approach toward Iran that ultimately failed to curb Tehran’s nuclear ambitions or regional influence. An analysis of this period identifies several strategic missteps that contributed to the expansion of Iran’s nuclear program, increased military assertiveness, and a weakened international coalition opposed to Iranian activities.

The Trump administration’s 2018 withdrawal from the Joint Comprehensive Plan of Action (JCPOA) marked a pivotal moment. Despite repeated confirmations of Iranian compliance by the International Atomic Energy Agency and U.S. intelligence agencies, the decision to exit the agreement came without a clear alternative framework. This move eliminated a critical mechanism for monitoring and limiting Iran’s nuclear activity. Former Central Command commander Gen. Joseph Votel warned that the withdrawal deprived the U.S. of essential oversight tools, while European officials, including the EU’s Federica Mogherini, cautioned it could destabilize global security. Following the exit, Iran accelerated uranium enrichment and deployed advanced centrifuges, reducing transparency and cooperation with inspectors.

The administration’s “maximum pressure” campaign relied heavily on escalating economic sanctions intended to coerce Iran into renegotiating the deal on more restrictive terms. However, experts and analysts contend that the strategy lacked an accompanying diplomatic effort. As noted by the RAND Corporation, the approach entailed “maximum pressure” but insufficient diplomacy. Iranian voices, such as strategist Hossein Mousavian, argued that the sanctions unified Tehran’s hardliners and moderates against the United States, while harmful effects on civilian populations fueled anti-American sentiment without altering the behavior of Iranian elites.

U.S. assessments also underestimated Tehran’s deterrence strategy, which emphasizes asymmetric retaliation. In response to increased U.S. pressure, Iran engaged in actions such as attacks on oil tankers in the Gulf, drones striking Saudi oil installations, and missile launches by allied militias in Iraq and Syria. Notably, the 2019 strike on Saudi Aramco disrupted about 5 percent of global oil supply, illustrating Tehran’s capacity to inflict economic harm without provoking full-scale conflict. According to U.S. defense officials, these incidents exposed flaws in assumptions about American escalation dominance.

The targeted killing of Qassem Soleimani, commander of Iran’s Islamic Revolutionary Guard Corps Quds Force, in January 2020 further escalated tensions. While hailed by the Trump administration as reinforcing U.S. deterrence, Iran retaliated with ballistic missile strikes on a U.S. airbase in Iraq, injuring more than 100 personnel. Military leaders acknowledged the seriousness of the attack, which represented significant escalation. Analysts at the Center for Strategic and International Studies observed that the assassination eliminated a key Iranian strategist but failed to degrade Tehran’s proxy networks, which intensified their activities in Iraq and Syria. The U.S. lacked a clear post-strike strategy, exposing forces to ongoing retaliatory risks.

The unilateral U.S. withdrawal and subsequent punitive measures also fractured the coalition built around the JCPOA. European allies criticized the American approach and developed alternative financial channels, such as the Instrument in Support of Trade Exchanges (INSTEX), to circumvent U.S. sanctions, signaling a deepening transatlantic divide. European diplomats described Washington as isolated from its traditional partners, reducing the effectiveness of pressure on Iran and allowing Tehran to portray itself as abiding by international norms.

Additionally, the U.S. administration’s insistence on Iran first accepting a broad set of stringent demands, characterized by some observers as tantamount to capitulation, left little room for meaningful negotiation. Iranian Foreign Minister Javad Zarif asserted that the approach was designed to make talks impossible. Absent diplomatic engagement, sanctions became an end rather than a means to resolve disputes.

Throughout the period, domestic political considerations shaped the U.S. approach, often at the expense of strategic clarity. President Trump’s unpredictability, exemplified by the public cancellation of planned military retaliation via social media in 2019, sowed confusion among allies and adversaries alike. Iranian leaders interpreted this as weakness, diminishing deterrence rather than reinforcing it.

By the end of Trump’s tenure in 2021, Iran had enriched more uranium, deployed more sophisticated nuclear technologies, strengthened ties with Russia and China, and adopted a more assertive regional stance. Meanwhile, the United States faced diminished international support and reduced leverage over Tehran. Analysts concluded that the policy of “maximum pressure” had instead yielded “maximum resistance,” reflecting a fundamental gap between ambitious aims and the lack of coherent diplomatic, military, and political strategy.