Trudeau was angered Trump utilized the rarely invoked "national security" provision to justify the tariffs, and in doing so was alluding that Canada was a threat to US national security.
Asked if the administration will respect decisions from the World Trade Organization on tariffs, Kudlow said that "international multilateral organizations are not going to determine American policy".
"We'll all be behind him to support this essential initial initiative in the fight for global denuclearization, " Macron said.
Canadian Prime Minister Justin Trudeau called President Trump's new tariffs "insulting" earlier this week, wondering why the USA was suddenly treating its Northern neighbor like a national security threat.
The relationship has reportedly frayed to the point where Trump was considering sending Vice President Mike Pence to the G7 summit in his place, according to a Washington Post report.
The Prime Minister also raised strong concerns about the U.S.'s Section 232 investigation on automobile imports, given the mutually beneficial integration of the Canadian and American auto industries. The group of nations has a secondary list of items that will be subjected to a new tariffs in three years or possibly sooner, if the WTO rules in the EU's favor.
Top Republican Paul Ryan says Trump shouldn't pardon himself
And if you're at school and keen to get out of a lesson, you'll definitely want to get the lawyers on to it. Attorney Preet Bharara also told State of the Union it would be "outrageous" for Trump to pardon himself.
The Trump administration imposed 25 and 10 per cent tariffs on Canadian steel and aluminum and the Trudeau government responded with dollar for dollar counter duties which are set to kick in July 1.
Canada and Mexico already have retaliated against a range of USA exports and the European Union has promised to do so as well, raising the specter of a tit-for-tat escalation.
The reports do not say what types of penalties are being looked at.
But before leaving Washington, he made clear that he too has no intention of backing down on his plan to rebalance trade by imposing tariffs on steel, aluminum and other goods imported from U.S. allies. But U.S. shares rose on Wednesday.
Few though expect Mr Trump to back down, prompting fears of a bad-tempered summit and the prospect of leaders not agreeing the traditional end-of-summit communique. European allies have urged Trump to reconsider.
Now the G7's future is in doubt, with Trump's imposition of steel and aluminum tariffs on his G7 partners, as well as broader disagreements on the trade and climate change. France would also oppose any wording that described the Iran pact as obsolete, the official added.
Corker, whose state of Tennessee is home to foreign and domestic auto plants, questioned Trump's national security justification in a statement last week.