The Kyoto Protocol is an international agreement linked to the UNFCCC aimed at fighting global warming. It commits industrialized nations to reduce greenhouse gas emissions. The major distinction between the Protocol and the Convention is that the Convention encouraged emissions reductions while the Protocol commits countries to do so. The Protocol was negotiated in 1997 and entered into force in 2005 after Russia ratified it. It sets emissions reduction targets for 37 Annex I countries and allows flexible mechanisms like emissions trading to lower costs of achieving targets.