The interim US–Iran truce came under sharp strain Saturday after attacks on a key US ally and vessels transiting the Strait of Hormuz, raising fresh risks for regional stability and energy flows.

Bahrain, home to the US Fifth Fleet, announced that Iranian drones attacked its territory. The country’s Ministry of Foreign Affairs called the strike “a blatant violation” of its sovereignty, Bahrain News Agency reported.

The UK Maritime Trade Operations (UKMTO) said on Saturday that an unidentified projectile struck a tanker in the strait. The vessel sustained damage to its bridge, with all crew reported safe, the naval group said. It advised ships to "transit with caution."

The Joint Maritime Information Center increased the security threat level in the strait to "substantial" following attacks on merchant vessels. It published a warning area for potential mines spanning much of the usual transit route.

Iran warned that safe passage through the strait could not be guaranteed without coordination with Tehran, Fars News Agency reported. Vessel-tracking data, however, showed that multiple ships continued to transit the waterway Saturday morning, Bloomberg reported.