Sea Shepherd activists have taken to shooting rotten butter at Japanese whaling factory ships in order to harass them.

“The crew deployed over two dozen bottles of rotten butter, sending a stench throughout the whale-killing ship that will remain for days,” the group said.

They said they also threw packets of an undisclosed “slippery chemical” on to the deck of the Nisshin Maru. This will make it very difficult to cut up whales.

The captain of Sea Shepherd has labeled the technique “non-violent chemical warfare.”