China has bought about a quarter of what would be expected this year if it was going to meet the targets in the deal.
Milk prices have been volatile with the trade war and now the coronavirus pandemic, and dairy farmers are stretched thin.
The move escalates a trade dispute over how much tech companies can be taxed outside their home countries.
The Trump administration is denouncing the fact that the tax levels vary greatly between members of the global trade body.
Tariffs from 2018 made raw metals from outside the country more expensive. Now finished products could get extra taxes, too.