The legality of white phosphorus depends entirely on how and where it is deployed:

Legal Use: It is legal when used strictly on an open battlefield as a smoke screen to obscure troops or for illumination.

Illegal Use: It is illegal to use it to directly target human beings, or to deploy air-dropped incendiary weapons inside populated civilian areas.

Human rights organizations argue that firing it into residential municipalities in southern Lebanon constitutes an unlawful, indiscriminate attack under international humanitarian law because it foreseeably harms civilians.