Immigration reduction refers to a social movement in the United States that advocates a reduction in the amount of immigration allowed into the country. Steps advocated for reducing the numbers of immigrants include advocating stronger action to prevent illegal entry and illegal immigration, and reductions in non-immigrant temporary work visas (such as H-1B, L-1 and J-1). Some advocate tightening the requirements for legal immigration requirements to reduce numbers, or move the proportions of legal immigrants away from those on family reunification programs to skills-based criteria. What separates it from standard immigration reform is that reductionists see immigration as a major source of social, economic, and environmental problems, and seek to curtail current immigration levels.