WASHINGTON -- The United States has just sworn in its next ambassador to Canada at a moment of trade tensions between the countries, with mushrooming disputes running parallel with the renegotiation of NAFTA.

Kelly Knight Craft was sworn in on the same day that the U.S. Commerce Department clobbered Canada's aerospace giant Bombardier with a preliminary duty of 219 per cent, atop recent duties on softwood lumber.

The philanthropist and Republican donor was sworn in by U.S. Vice-President Mike Pence at the White House, surrounded by a large gathering of Washington power-players.

Pence has reassured Canada that NAFTA negotiations will produce a, "win-win-win," and he sounded a similarly positive note as he swore in Craft on Tuesday.

"President Trump is firmly committed to strengthen our relationship with our treasured ally, friend, neighbour, Canada. One of the clearest signs of that commitment is President Trump's choice of Kelly Craft as America new Ambassador," Pence said.

"This is also a momentous time in our relationship with our neighbour as we work with Canada and Mexico to modernize NAFTA. We know you will play a pivotal role in those negotiations and discussions as they go forward."

Negotiators for the NAFTA countries were in Ottawa working on the third round of talks toward an updated continental trade deal.

Also present at the ceremony were U.S. Senate Leader Mitch McConnell, a fellow Kentuckian, and his wife, Transportation Secretary Elaine Chao; University of Kentucky basketball coach John Calipari; several lawmakers; former ambassadors under Barack Obama, Bill Clinton, and George W. Bush; Craft's family; White House staffer Kellyanne Conway; former Trump campaign manager Corey Lewandowski; and Kirsten Hillman, Canada's new deputy ambassador to the U.S.

Craft warmly thanked her husband, a coal baron and major GOP donor, who will accompany her to Ottawa.

"(We will be) on a mission of service," Craft said.

"Service on behalf of the professionals in our embassy, ... service on behalf of many business relationships that make Canada such an important part of our economy, service on behalf of all of you who deserve effective representation of our interests in the capitals of this world."

The U.S. Department of Commerce imposed duties over what it deemed to damaging subsidies to Bombardier. This comes atop duties on softwood lumber, and a failure so far to get a deal that would end the latest dispute in that sector.

"The U.S. values its relationships with Canada, but even our closest allies must play by the rules," said Commerce Secretary Wilbur Ross, announcing the aerospace duty.