"We will put tariffs on Harley-Davidson, on bourbon and on blue jeans - Levi's", Juncker added.
"If the European Union wants to further increase their already massive tariffs and barriers on USA companies doing business there, we will simply apply a Tax on their Cars which freely pour into the U.S", Trump tweeted.
Canada's leadership said they would retaliate with tariffs on U.S. exports, and European leaders said they would as well, targeting Kentucky bourbon, Harley Davidson motorcycles, and blue jeans.
He also criticised Europe in remarks at a fundraiser, according to video posted online on Saturday, and suggested they would not increase tariffs.
Ross is dismissing the fallout from potential retaliation by the European Union.
"The federal government must stand and fight, here and now, against this threat by the USA government and supporting stakeholders", he said.
The cross-border trade file under Trump - including the NAFTA talks - has been challenging for Canadian government representatives.
The looming trade war comes as negotiations over a US-UK Open Skies agreement appear to have got off to a bad start.
Gareth Stace, the director of trade body UK Steel, said: "In short, these measures would cause serious damage to the prospects of many steel producers here". "Auto sales have flattened in recent months, and manufacturers are not prepared to absorb a sharp increase in the cost to build cars and trucks in America".
In 2002, then US President George W Bush imposed safeguard duties between 8-30% safeguard duty before the elections to the Congress and was forced to remove them in November, 2003 after the WTO authorized more than US $ 2 billion in sanctions on American goods because of the illegal safeguard duties.
Meanwhile, in a reference to the US's opioid crisis, Trump said Mexico must "do much more" to stem the flow of illegal drugs into the US.
The US has made clear that no countries will be exempted from the tariffs, raising acute fears for British exporters.
Why go after European cars?
Bring it on, Trump seemed to say.
Last time he spoke to WFMZ, he was elated about tax cuts.
Politicians aren't the only ones worries about what these tariffs could mean for Canada's economy.
It's still unclear at this stage.
"We're sort of the middle man", Keith said.