On June 15, 2026, a leaked internal memo from the U.S. Department of Defense revealed that former President Donald Trump’s 2018 decision to withdraw from the Iran nuclear deal—formally known as the Joint Comprehensive Plan of Action (JCPOA)—had “accelerated regional instability in ways that continue to reverberate across Middle East geopolitics.” The document, obtained by Foreign Affairs, underscores a long-debated assessment: that Trump’s unilateral actions marked a pivotal shift in U.S.-Iran relations, with consequences still unfolding nearly a decade later.
What led to the escalation?
The 2018 withdrawal from the JCPOA, framed by Trump as a rejection of a “bad deal” that failed to address Iran’s ballistic missile program and regional aggression, triggered a cascade of diplomatic and economic fallout. According to a BBC analysis, the move removed sanctions relief for Iran, prompting the country to resume uranium enrichment and abandon key nuclear restrictions. “This wasn’t just a policy shift—it was a strategic miscalculation,” said Dr. Trita Parsi, president of the National Iranian American Council. “
Trump’s approach ignored the nuanced balance of power in the region. By isolating Iran, he pushed it closer to adversaries like Russia and China, which now hold greater influence over Middle East security.
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The immediate aftermath saw Iran’s Supreme Leader Ayatollah Ali Khamenei declaring the U.S. “a dying empire,” while the International Atomic Energy Agency (IAEA) reported a 300% increase in Iran’s enriched uranium stockpile by 2019. The U.S. also imposed “maximum pressure” sanctions, targeting Iran’s oil exports and financial systems. These measures, according to a Reuters investigation, crippled Iran’s economy, contributing to a 40% depreciation of the rial and widespread food shortages.
How did it reshape regional alliances?
The void left by U.S. policy shifts allowed Iran to deepen ties with Russia and China, both of which have since become critical suppliers of military and economic support. A 2025 CSIS report noted that Russia’s arms exports to Iran rose by 60% between 2019 and 2024, while Chinese investments in Iran’s energy sector exceeded $12 billion by 2023. “This isn’t just about trade,” said Dr. Kaveh L. Afrasiabi, a former U.S. diplomat. “
The U.S. lost its ability to shape the region’s security architecture. Instead, Iran now operates as a broker between rival powers, leveraging its position to gain concessions from both the West and its adversaries.
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The shift also strained U.S. relationships with traditional allies. Saudi Arabia, which had previously sought to balance Iranian influence, reportedly grew wary of American inconsistency. In 2020, the kingdom began informal talks with Iran over Yemeni ceasefire agreements—a move that underscored the erosion of U.S. diplomatic authority. “America’s credibility as a security provider has been damaged,” said Dr. Ray Takeyh, a senior fellow at the Council on Foreign Relations. “
The region now views the U.S. as a less reliable partner, which has emboldened actors like Iran and Turkey to act more aggressively.
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What economic consequences persist?
The economic fallout of Trump’s policies has had lasting effects on global markets. The 2018 sanctions, combined with Iran’s resumption of nuclear activities, contributed to a 20% spike in global oil prices in 2019, according to the U.S. Energy Information Administration (EIA). While prices stabilized after the 2021 revival of the JCPOA under President Joe Biden, the agreement faced immediate challenges, including U.S. demands for stricter inspections and Iran’s insistence on lifting sanctions in full.
The tech sector has also felt the ripple effects. A New York Times analysis highlighted how U.S. export controls on advanced semiconductor technology—tightened under Trump—have forced Iranian tech firms to rely on black-market components. “This has created a parallel digital economy in Iran,” said Dr. Hadi Hajihosseini, an economist at the University of Tehran. “
While it’s driving innovation in some areas, it’s also isolating Iran from global supply chains, which could hinder long-term growth.
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Why does this matter today?
The legacy of Trump’s Iran policy is evident in the current geopolitical landscape. The 2026 conflict in the Red Sea, where Iranian-backed Houthi rebels have targeted commercial vessels, has drawn comparisons to the 1980s Iran-Iraq
