UK warns Iran against blockading Strait of Hormuz or attacking US bases amid rising tensions

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Jun 23, 2025
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Britain has warned Iran that firing on US bases or closing the Strait of Hormuz would be a "catastrophic mistake," as tensions rise following US airstrikes on Iranian nuclear sites and Iranian lawmakers endorse a measure to block the key shipping route.

Britain issued a warning to Iran on Monday, cautioning that any move to fire on US bases in the Middle East or to blockade the Strait of Hormuz would be a “catastrophic mistake.” The statement comes after the Iranian parliament endorsed a measure to close the narrow, strategically significant waterway, which handles about 30 percent of global seaborne oil shipments. The final decision on the closure rests with Supreme Leader Ayatollah Ali Khamenei, as Iran considers its response to recent US airstrikes on Iranian nuclear facilities.

UK Foreign Secretary David Lammy told the BBC that he had urged his Iranian counterpart not to escalate the conflict and said he believed Iran’s supreme leader understood the risks. “It would be a catastrophic mistake. It would be a mistake to blockade the Strait of Hormuz. I think [Khamenei] gets that and understands that ... I'm an optimist,” Lammy said.

US Secretary of State Marco Rubio also commented on Sunday that blocking the passage would be “economic suicide.”

The UK continues to press for de-escalation following US strikes on three Iranian facilities intended to prevent Iran from acquiring a nuclear weapon. Iran maintains its nuclear program is peaceful, though the International Atomic Energy Agency found Iran non-compliant with nuclear obligations earlier in June.

In a joint statement with French President Emmanuel Macron and German Chancellor Friedrich Merz, UK Prime Minister Keir Starmer called on Iran to engage in negotiations and reach an agreement addressing concerns about its nuclear program. In a subsequent call with President Donald Trump, Starmer discussed the need for Iran to return to the negotiating table and make progress toward a lasting settlement, according to Downing Street.

While the UK was informed in advance about the US strikes, ministers have not disclosed whether Britain would participate in any further conflict. Defense Minister Luke Pollard confirmed the UK was not involved in the military action and declined to comment further on the US operation.

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