It would be more appropriate to restrain the asset purchases because this where the offending country is distorting the market while using capital controls to prevent the US from responding in kind. Presumably, to the extent that the proceeds of import sales are used to purchase US goods and service exports, America is content to receive imports, so applying a tariff to all the imports from the offending country would represent overkill. Also, in practice I doubt that any tariff would be uniform; it would probably vary according to the strength of lobbying from domestic producers and importers.

While I think that for the US to resist official capital inflows is like looking a gift horse in the mouth, I do agree that if the US is not happy about other countries dollar exchange rate policies and those countries have a closed capital account that prevents the US from counter-intervention, the most appropriate measure is to restrict or penalise their capital inflows rather than their imports into the US. That avoids disturbing the relative competitiveness of various imports and rewarding lobbying by particular US industries.

Are you offering a discount? Italian bonds are mainly owned by Italians (but perhaps also in a few offshore accounts owned by Italians). Incidentally, one of the problems of the EUR is that it is hard to let countries default and hard to keep them solvent. Perhaps the Italians should resurrect Mussolini. He made the trains run on time. Italy will have a hard time negotiating concessions (and every country has a wish list) in Brussels this is setting a bad example for zero-sum cowboys like the Poles, etc. Some day, like in any exclusive club, a misbehaving member will be suspended or thrown out.