There were two main concerns about the CDM (Carbon Trust, 2009, pp. 14–15). One was over the additionality of emission reductions produced by the CDM (see the section on "additionality"). The other was whether it would allow rich, northern countries, and in particular, companies, to impose projects that were contrary to the development interests of host countries. To alleviate this concern, the CDM requires host countries to confirm that CDM projects contribute to their own sustainable development. International rules also prohibit credits for some kinds of activities, notably nuclear power and avoided deforestation.