Agence France-Presse, citing experts, reported that satellite images of the formation of possible oil stains near the Strait of Hormuz after U.S. attacks on oil tankers suspected of links to the Islamic Revolutionary Guard Corps indicate.

European Copernicus program images on Wednesday and Thursday show brown streaks on the surface of the water, about 20 kilometers off Iran’s coasts and to the east of the Strait of Hormuz. Experts described these images as a strong sign of possible pollution caused by the vessels.

Agence France-Presse emphasized that satellite images alone do not prove the presence of hydrocarbon materials or the precise source of the pollution.

The two identified patches begin in locations from which the oil tankers “Risco” and “Kailuo” broadcast their last signals before sinking. One researcher said that, given the time and location, Risco is one of the possible sources of the contamination.

The U.S. Army had previously announced that it had destroyed five oil tankers in the Sea of Oman. The locations of the possible oil slicks are also recorded near the coral reefs registered with the Ramsar Convention.