Unilateral imposition of such a tax would offer little to no climate benefit. The idea that China and India would follow the US lead on this issue is absurd. As I like to say, China is as likely to follow the example of the U.S. on carbon controls as it has with regard to human rights, civil rights, religious freedoms, etc. China and India will act on their economic interests, and they've been quite honest about that.
Fallacy: impossible expectations