Since the 1960s, tariffs — or import taxes — have emerged from negotiations between dozens of countries. Trump wants to seize the process. “Obviously, it disrupts the way that things have been done for a very long time,

Commission President Ursula von der Leyen said unjustified tariffs would prompt "proportionate and decisive countermeasures", echoing her vow on Tuesday of a "firm and proportionate" response to Trump's decision to impose tariffs on all steel and aluminum imports.

Britain entered a rare deficit in its goods trade with the United States at the end of last year, according to data published on Thursday that London will hope bolsters its case against the imposition of new tariffs by President Donald Trump.