For what it's worth, here are the cases filed by the U.S. since Jan 20, 2009:
And here are the cases filed against the U.S. since Jan 20, 2009:
It may be worth noting that 3 of the 5 cases filed against the U.S. were trade remedy cases; without trade remedies, it's 2 filed by and 2 filed against. Will the U.S. ever make it a regular practice to challenge foreign trade remedy actions?
ADDED: For example, this one: