Although the Montreal Protocol regulates the phasing out of HCFCs, there was no international agreement on the regulation of HFCs until late 2016 when the Kigali Amendment under the Montreal Protocol was signed, which has put compulsory phase wise phasing out of CFC gases. Efforts are ongoing to develop a global approach for the control of HFCs. Most recently, this has taken the form of a declaration of support for a global phase-down as part of the outcomes of the "Rio+20" United Nations Conference on Sustainable Development.