USTR asked to identify $200 billion in goods for 10% tariffs, China vows to respond.

Proposal for a yuan crude oil futures contract gains attention.

Proposal for a yuan crude oil futures contract gains attention.

Supporters hope Tobin tax would reduce yuan speculation; opposition sees FX tax as 'contrary to the spirit of a freely usable currency.'

Supporters hope Tobin tax would reduce yuan speculation; opposition sees FX tax as 'contrary to the spirit of a freely usable currency.'

Discussion next week may push central bankers to do a better job of coordinating policies across national borders.