Tree spiking is a form of sabotage which involves hammering a metal rod or other material (commonly ceramic) into a tree trunk in order to discourage logging. A metal saw blade hitting an embedded spike could break or shatter, making it uneconomic to fell those trees. Spikes could possibly injure or kill loggers. It is often referred to by critics as a form of Eco-terrorism, because its tactics are to intentionally harm, or coerce log workers by fear of physical harm, from sawing at the tree.