Acts of sabotage are aimed at threatening or destroying life and property, or at hampering or hindering specific activities. Sabotage is used during war, and is also used by terrorists, guerrillas, resisters and criminals during peace-time. Deliberate sabotage of projects which harm the earth and living systems, sometimes called "monkeywrenching", is a hardline ecological activity. These activities would include sinking metal spikes into trees to prevent them being felled or incapacitating bulldozers. Sabotage is also widely used among the more radical animal welfare activists.