"Refugees as weapons", or "Weapon of Mass Migration" is a term used for organised mass exodus of refugees from one state to a hostile state as a "weapon" against that 'targeted' state. Weaponized migration occurs when a challenging state or non-state actor exploits human migration—whether voluntary or forced—in order to achieve political, military, and/or economic objectives. Kelly Greenhill counts 56 attempts (1951 to 2006) to employ the direct or indirect threat of mass migrations as a non-military instrument of influence.