Two Russian cargo ships were damaged during a storm as they were delivering 4,300 tonnes of fuel oil each to the Russian navy in the Kerch Strait between mainland Russia and illegally annexed Crimea last week.

A rescue operation involving 50 personnel, helicopters and tugboats was mounted to help.

Dr. Paul Johnston, head of Greenpeace Research Laboratories, based at the University of Exeter in the United Kingdom, said that the weather conditions would determine the scale of the challenge to clean the oil spills.

“If [the spill] is driven ashore, then it will cause fouling of the shoreline, which will be extremely difficult to clean up,” he said.

The type of oil will also affect the scale of the environmental impact.

“Heavy residual fuel oils will tend to cause more visible damage than refined fractions and marine gas oil, which will tend to disperse and break up quite rapidly,” the expert said.

Dr. Johnston urged authorities to try to prevent the sinking of the tankers because this could release oil and petrochemicals into the Kerch Strait over a longer time span.

In 2007, a Russian tanker spilled 1,200 tonnes of oil in the same region, causing severe damage to the environment, Greenpeace said in a statement.

The Kerch Strait is an important route for various Russian exports such as crude oil, which has been heavily sanctioned by allies of Ukraine since Moscow invaded the country in February 2022.