UK rules out war with Iran, Strait of Hormuz blockade, says PM Starmer

Prime Minister Keir Starmer announced Britain does not support a war with Iran or a blockade of the Strait of Hormuz. The odds of the UK striking Iran by April 30 sit at 3.6% YES.

Starmer’s statement matches the UK’s existing defensive posture in the US-Israel-Iran conflict. The UK military action by April 30 market showed no meaningful price movement, holding at a low probability of UK offensive involvement. The sub-market for other countries engaging militarily against Iran is at 9.2% YES for action by April 15, with slight recent movement.

Daily USDC volume in the UK strike market is $261, a thin level of activity. The order book depth means it would take $427 to move the price by 5 percentage points, so even modest trades could shift the odds noticeably. The largest move in related markets was a 3-point spike, suggesting traders are cautious but reactive to military developments.

Starmer’s declaration matters because it sets a clear expectation that the UK will not shift to an offensive role, which reduces the probability of escalation involving British forces and may factor into other nations’ military calculations. Buying YES at 3.6¢ pays $1 if the UK strikes Iran by April 30, a 27.8x return. With 18 days left and the UK government explicitly ruling out offensive action, traders would need strong evidence of a policy reversal to justify that bet.

Watch for statements from the UK Ministry of Defence or new diplomatic moves in the region. Any shift in rhetoric or military positioning could move this market quickly given the thin order book.

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