An "unknown projectile" struck a tanker off the coast of Oman, a British maritime agency said on Tuesday, as Iran and the United States exchanged fire over control of the Strait of Hormuz.The UK Maritime Trade Operations agency said it "received multiple reports that a tanker... has been struck by an unknown projectile in the Strait of Hormuz," adding that the incident occurred eight nautical miles (15 km) northeast of Limah, Oman.On Tuesday, Iran's Revolutionary Guards they stopped two "non-compliant oil tankers" attempting to transit the Strait of Hormuz, state news agency IRNA reported."Two non-compliant oil tankers attempting to pass through the unsafe southern route of the Strait of Hormuz were stopped after explosions caused extensive fires aboard them," the Guards said in a statement carried by IRNA.On Monday (July 20), two oil tankers managed by Greek shipping company Dynacom Tankers were reportedly struck by projectiles off the coast of Oman, underscoring the growing risks to commercial shipping as fighting between the United States and Iran intensifies around the Strait of Hormuz.