Strait of Hormuz Disruptions: Historical Conflicts Threaten Global Oil Flows
The ongoing war between the United States, Israel, and Iran has once again placed the Strait of Hormuz at the centre of a geopolitical storm. Iran has effectively halted nearly all maritime traffic in this crucial waterway, which connects the Persian Gulf to global oceans, severing a vital artery for the world's oil supply. Attacks on commercial vessels and threats of further strikes have prevented tankers from transporting oil, gas, and other commodities through the passage. This blockade has forced some of the world's largest oil producers to cut output, as their crude has no viable export route.
A History of Weaponization
This is not the first instance where the Strait of Hormuz has been leveraged as a strategic weapon. Previous ship seizures and regional conflicts have repeatedly raised alarms for commercial shipping, at times severely impeding safe passage. Over the years, Iran has frequently threatened to close the strait in response to international sanctions and escalating tensions, though it has historically stopped short of a complete shutdown. Even amid the current conflict, which has stalled the bulk of traffic, maritime data indicates that dozens of vessels have still managed to navigate the waterway.
While both Iran and Oman hold territorial claims in the Strait of Hormuz, its narrow shipping lanes are internationally recognized as waters open to all vessels. Nevertheless, Tehran wields considerable influence over the passage due to its substantial military presence in the area and control over key islands. The latest clash, now entering its third week following U.S. and Israeli strikes that resulted in the death of Iran's supreme leader, has had profound repercussions for energy markets. Prior to the war, approximately one-fifth of the world's oil transited through the Strait of Hormuz, and the ensuing supply constraints have sent fuel prices skyrocketing.
Historical Instances of Disruption
1980s: The Iran-Iraq 'Tanker War'
During the protracted and brutal eight-year war between Iran and Iraq in the 1980s, both nations targeted tankers and other ships in and around the Strait of Hormuz. Naval mines were deployed at various points to obstruct traffic. The United States became embroiled in the so-called Tanker War, with the U.S. Navy engaging in a one-day battle against Iran in 1988. In a tragic incident, the U.S. later shot down an Iranian commercial airliner, mistakenly identifying it as a fighter jet, resulting in 290 fatalities.
The strait did not close entirely during this period. U.S. naval forces provided escorts for Kuwaiti oil tankers to shield them from Iranian assaults. Despite these measures, the passage became exceedingly perilous, leading to significant disruptions in shipping operations.
2011–2012: Nuclear Sanctions and Closure Threats
In late 2011 and into 2012, Iran threatened to close the Strait of Hormuz in retaliation for new Western sanctions targeting its nuclear development programme. The European Union imposed a ban on purchasing Iranian oil, while the United States sanctioned Iran's energy sector and prohibited transactions with its central bank. These measures prompted other nations to reduce their imports of Iranian crude.
Iran ultimately moderated its threats and did not proceed with closing the strait. However, the ensuing turbulence and shifts in supply triggered volatility in oil prices. Brent crude, the international benchmark, traded above $100 per barrel in December 2011 and for much of 2012, peaking at over $126 in March 2012 before moderating later in the year.
2018: U.S. Withdrawal from the Nuclear Accord
In May 2018, during his first term, U.S. President Donald Trump withdrew from the Obama-era nuclear accord with Iran and reinstated sanctions. Although some waivers were granted, Trump pledged to eventually eliminate all Iranian oil exports. In response, then-Iranian President Hassan Rouhani reiterated threats to close the Strait of Hormuz.
Once again, Iran refrained from closing the strait. Despite periods of volatility and production pressures on OPEC members, Brent crude ended the year trading at nearly $54 per barrel, a decline from approximately $75 when Trump announced the U.S. withdrawal in May 2018.
2019-2025: Ship Seizures and Attacks
The U.S. Navy attributed a series of limpet mine attacks on vessels near the strait in 2019, which damaged multiple tankers, to Iran, along with a fatal drone strike on an Israeli-linked oil tanker in 2021. Tehran denied involvement at the time. These hostilities drove up insurance costs and heightened anxieties among shipping companies.
Concurrently, Iran seized several vessels in the waterway, including foreign oil tankers accused of smuggling fuel as recently as late last year, according to state media. Additional incidents included the capture of a Portuguese-flagged cargo ship in 2024 and the detention of two Greek tankers for months in 2022. Despite these actions, the strait remained open throughout this period.
June 2025: The 12-Day Israel-Iran War
Concerns over a potential Strait of Hormuz closure escalated during last year's 12-day war between Israel and Iran, especially after the U.S. entered the conflict with bombings targeting Iranian nuclear and military sites.
Iran did not close the strait, and oil prices did not experience sustained increases. Although prices spiked initially, a significant sell-off occurred as traders discounted the likelihood of attacks on crude shipments. By the war's conclusion, Brent crude was trading below $67 per barrel, slightly lower than pre-conflict levels.
