China has resisted mandatory reductions in emissions, arguing that it is still a developing country and needs to balance environmental improvements with maintaining economic growth.
And the U.S. has refused to impose tough mandatory reductions on its own.
Democrats said that they had proposed a significant mandatory reduction in imports during the energy policy debate only to see the plan rejected by Republicans.
But the mandatory reduction, enacted in 1990, was accompanied with specific measures that cut costs.
For instance, nearly five years behind some of its northern neighbors, Italy is now considering mandatory reductions in automobile emissions.
It would require prompt and mandatory reductions by 2012 in gas emissions to levels well below those in 1990.
Mr. Bush said a mandatory reduction could hurt what he called an already stressed energy market.
Even the United States Senate has committed itself, on paper, to a program of mandatory reductions, with hearings to begin later this month.
The answer is 'no', and this is why we have proposed the mandatory reduction by 2012.
The treaty calls for the mandatory reduction of greenhouse gases by industrial nations.