Greenpeace is known for its direct actions and has been described as the most visible environmental organization in the world.[11][12] Greenpeace has raised environmental issues to public knowledge,[13][14][15] and influenced both the private and the public sector.[16][17] Greenpeace has also been a source of controversy;[18] its motives and methods (some of the latter being illegal) have received criticism,[19][20] including an open letter from more than 100 Nobel laureates urging Greenpeace to end its campaign against genetically modified organisms (GMOs).[21] The organization's direct actions have sparked legal actions against Greenpeace activists,[22][23] such as fines and suspended sentences for destroying a test plot of genetically modified wheat[24][25][26] and damaging the Nazca Lines, a UN World Heritage site in Peru.[27]