Al Jazeera reported that the United States and Iran have been mutually attacking oil tankers and vessels in and around the Strait of Hormuz, raising concerns about a catastrophic oil spill in the Gulf region. On September 8, the U.S. attacked five Iranian oil tankers, following an attack on three others on September 5. Iran also claimed to have attacked three oil tankers traveling on "unauthorized routes" in the strait, as well as three U.S.-affiliated vessels. As of September 7, 42 oil tankers were awaiting passage in the Strait of Hormuz, 18 of which were carrying oil, with an estimated total oil volume of 1.76 million cubic meters (approximately 11.1 million barrels), equivalent to 11% of global daily oil demand. A major spill would cause severe damage to the fragile marine ecosystem.