The United Kingdom's confirmation that it will allow the United States to use its bases for defensive operations is a critical turning point in the escalating crisis in the Strait of Hormuz.
The immediate trigger for this action has been the severe disruption to global shipping since late February. After Iran began threatening commercial vessels, traffic through this vital waterway nearly ground to a halt. The situation worsened dramatically when maritime insurers, citing unacceptable risks, cancelled war-risk coverage for the entire Gulf region. This effectively paralyzed trade, creating immense economic pressure on global markets and supply chains.
In response, the UK and its allies have carefully constructed a legal and political framework for intervention. The first pillar is the legal justification: on March 1, the UK government published its position, framing the potential military action as collective self-defence under Article 51 of the UN Charter. This defines the missions as limited and defensive, aimed solely at protecting international shipping. The second pillar is international support; a UN Security Council resolution on March 11 condemning Iran's actions provided crucial political backing, legitimizing the mission to reopen the strait.
These diplomatic moves have been paralleled by concrete military preparations. The arrival of US B-1 and B-52 bombers at RAF Fairford in early March was a clear signal of intent. Today's announcement is not just a statement of policy but the operational green light for missions designed to degrade Iran's coastal anti-ship missile and drone launching capabilities.
However, this crisis did not emerge overnight. It is rooted in a pattern of escalating provocations, including Iran's repeated seizures of oil tankers throughout late 2025. These actions demonstrated Tehran's willingness to use maritime coercion as a strategic tool. On a structural level, the UK's forward-thinking agreement with Mauritius in May 2025 to secure long-term access to the Diego Garcia base proved essential, providing the strategic depth needed for a rapid response.
The market reaction has been swift and severe. Oil benchmarks like Brent and WTI surged by nearly 50% between late February and mid-March, reflecting a significant risk premium as traders priced in a prolonged closure of the strait. Every report of potential military action or diplomatic progress has caused sharp price swings, underscoring the high stakes involved for the global economy.
Ultimately, the UK's decision is the operational hinge that allows the US to execute a campaign to restore freedom of navigation. The success or failure of these defensive missions will directly determine whether the global energy market stabilizes in the coming months or faces a much larger and more damaging shock.
- Strait of Hormuz: A narrow, strategic waterway between Iran and Oman, through which about a fifth of the world's oil supply passes.
- Article 51: A provision in the UN Charter that recognizes the inherent right of individual or collective self-defence if an armed attack occurs against a member of the United Nations.
- Risk Premium: The additional return an investor requires to hold a risky asset compared to a risk-free asset. In this context, it refers to the extra cost added to oil prices due to geopolitical instability.