Washington DC - Republican lawmakers are demanding that Canada pay $300 billion to the US government to cover shortfalls in its NATO defense spending commitments.

North Carolina Senator Thom Tillis said that while he is happy that Canada is meeting its 2% NATO defense spending commitment this year, it should pay back the US for the years during which this target wasn't met, Politico reports.

His comments came during the Halifax International Security Forum, which brought together a number of officials and international security experts.

"Can we do a makeup payment for the 20 years of shortfalls as well?" Tillis said during a Saturday panel. "It's fine to say you're about to catch up, but it's not fun to look past a $300 billion shortfall."

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Canada has doubled down on its commitment to spend 2% of its GDP on defense under Prime Minister Mark Carney, as the country seeks greater independence from the US.

Referring to former Prime Minister Justin Trudeau, Tillis said that "every prime minister has said the same thing, we're going to get to it. And they never got to it. As a result, there's a $300 billion shortfall in our mutual defense."

When asked about Tillis' comments, Canadian Defense Minister David McGuinty admitted that Canada's previous government had been "complacent" because other priorities had taken precedence over defense spending.

"Our defense muscles atrophied. Our security muscles atrophied. Call it the peace dividend, or the end of history," McGuinty said.

"We are rebuilding, rearming and reinvesting in the Canadian Armed Forces on a massive scale and at speed," he went on. "We're making generational investments into our security, our sovereignty and our resilience."

"We're hiring 15,000 soldiers. We're rebuilding 33 bases. We're moving on. We've got hundreds of aircraft on order. We've got destroyers being built."