Shipping flows through the Strait of Hormuz operated at reduced levels Sunday before President Trump announced an immediate US Navy blockade of the critical maritime chokepoint. Trump's Truth Social post followed failed US-Iran peace negotiations in Pakistan, with Tehran's control over Hormuz emerging as a sticking point that derailed talks aimed at preserving a fragile ceasefire.

Several tankers exhibited unusual behavior near Iranian islands, including abrupt U-turns and route changes. Traffic was confined to a narrow northern lane between the Iranian islands of Larak and Qeshm, while some outbound vessels followed Tehran-approved routes. Most vessels entering the region had ties to Iran or China, raising concerns about potential disruptions to global energy supplies.

The blockade announcement threatens global oil markets, as Hormuz handles about 20% of world's oil trade. Vessels "going dark" by disabling AIS transponders further complicates tracking. Trump vowed to interdict any ship that paid Iran's toll, escalating tensions in a region critical to global energy supplies and potentially triggering price spikes.