In the last two decades, the United States has fought at least two trade wars. Both times, the key battleground has been steel, and lobbyists have been in the thick of it. However, one would have to go back almost four decades, to 1981 in fact, to find another example of a US trade war, also with another Asian power – Japan, in which lobbyists have played as prominent  a role as they have done in the ongoing tiff with China, albeit over wider concerns…