The FTSE 100 opened in negative territory on Wednesday as geopolitical tensions in the Middle East flared anew.
US President Donald Trump issued a stern warning to Iran, threatening to "take over" the country after a series of surprise attacks effectively ended a brief pause in the conflict.
The escalation has reignited investor concerns over shipping routes and energy supply chains, particularly through the Strait of Hormuz.
London's benchmark index fell at the open, reflecting broader risk-off sentiment across European markets.
The sell-off mirrors recent volatility, with the FTSE 100 having already dipped earlier in the week as Trump threatened military action following the closure of the Hormuz strait.
Investors are now pricing in a higher probability of sustained disruption to global trade flows.