The former supreme allied commander of NATO says he agrees with Republican presidential candidate Donald Trump that non-U.S. allies need to step up to the plate and boost their military budgets.

"The two per cent goal is one that nations have set and I fully support it and I agree with Mr. Trump that nations should try to hit that two per cent goal," James Stavridis said in an interview with Terry Milewski on CBC Radio's The House.

Canada signed on to meeting that target in 2006 but has not reached the goal. Canada's spending comes in at one per cent of GDP, or roughly $20 billion a year, a figure that some have argued is too low to sustain a modern military force. Only five other countries of the 28 in NATO spend less.

Trump argued Wednesday, in his first major scripted public policy speech, that the United States foots the bill for far too much of the alliance's defence capacity, and other member nations — including Canada — are "freeloaders" for failing to contribute their fair share of domestic military spending.

"It's obsolete and too many people are getting a free ride," said Trump, who recently added to his delegate tally with a sweep of five primaries. "Frankly, they have to put up more money. We are paying disproportionately. It's too much. It's a different world than it was when we originally conceived of the idea."

Defence Minister Harjit Sajjan responded to the growing calls for Canada to meet the two per cent NATO spending target — not just from Trump, but current president Barack Obama and liberal-minded Democratic senators in Congress — saying Wednesday it would be considered as part of the defence review.

"Our commitment to NATO is rock-solid," he said again Friday when asked again to respond to Trump's comments.

"We are focused on spending our defence budget in a way that ensures the CAF has the capabilities needed to provide security for Canadians at home and abroad, and to carry out the important missions the government asks of it," a release from Sajjan said, noting that budget 2016 included predictable funding for the military.

NATO still relevant, former commander insists

Stavridis,who spent more than thirty years in the U.S. Navy and now serves as dean of the Fletcher School of Law and Diplomacy at Tufts University, supports Trump's aim — but takes issue with the harsh language Trump employs to chide key American allies.

"Would we like to see a bit more spending? Absolutely," the former top commander said. "But, I think we should be grateful for the spending we have and encouraging all to hit the two per cent goal.

"Overall, the United States spends $600 billion on defence and our non-U.S. NATO allies spends $300 billion a year on defence. That's more than China and Russia combined. So, it's not an insignificant contribution, and to call our NATO allies and partners, especially those like Canada, who have stood, fought and delivered and died on NATO missions, I think it is the wrong term to say 'freeloaders.'"

Stavridis also takes issue with Trump's characterization of NATO as an outdated multilateral alliance that does not meet the needs of the Western world.

The billionaire businessman has said that NATO does not adequately address the pressing problems of our time, notably Islamic terrorism, but is instead focused on an older adversary, Russia, and its continental encroachment.

Stavridis, a former naval commander, said that NATO is constantly addressing the "transnational threat."

Trump says other NATO members should increase military spending, to allow the U.S. to pull back. Canada has not met the NATO goal of two per cent of GDP on defence. (Canadian Press)

"I completely disagree that somehow NATO is obsolete. NATO stood against Islamic terrorism in Afghanistan, in Libya, in the Balkans, and counter-piracy missions. NATO adapted very, very well to the fall of the Berlin Wall," he said, while defending the alliance's current posturing against Russia.

"Should we be concerned about Vladimir Putin? I think the question answers itself when we look at his actions in invading Ukraine, and annexing the Crimea. That is a clear and present danger to the international system."

Prime Minister Justin Trudeau has reoriented Canada's mission against the Islamic State by pulling fighter jets back from the fight while boosting the number of special op trainers on the ground.

"When I was the supreme allied commander and had responsibility for 140,000 NATO troops in Afghanistan, I would look to the Canadian contingent for their superb work as trainers and mentors to the Afghan security forces," Stavridis said, noting that the shift is apt given Canada's military strengths.