World leaders are either defined by their accomplishments or by what they avoid doing. Usually, they are either hawks or doves. Both hawks and doves can be predictable, but they can also surprise us and step out of character. Then, all that's left is for history to define them.

As we approach the 15-year anniversary of 9-11, and as we reflect on the subsequent wars in Afghanistan and Iraq, we might also find ourselves remembering the kind of inaction that helped Canada's reputation as a force for good in the world.

Specifically, former Prime Minister Jean Chretien's refusal to take part in the war in Iraq was probably the most important decision a Canadian prime minister has made since Pierre Elliot Trudeau's War Measures Act in 1970. Hindsight being what it is, we now know the reasons to invade were dubious at best, fraudulent at worst. Chretien, no matter his motivations, made the right call, saving the lives of Canadian soldiers in the process.

Chretien was partially aided by a Republican administration in Washington that was largely seen as too conservative by most Canadians. George W. Bush wanted to invade without a UN mandate, and Chretien, less than a year away from retirement, refused to join the "coalition of the willing," saying in the House of Commons, "If military action proceeds without a new resolution of the (United Nations) Security Council, Canada will not participate."

Bush picked up the phone, and Chretien did not answer his call. The rest is history.

It cannot be stressed enough: the Bush administration, viewed as a band of neo-conservative war hawks, shielded Chretien from the kind of bad optics he would have had to deal with if it was a Democrat occupying the White House. An Al Gore administration would have been a more difficult refusal, if Gore had opted to invade at all.

A more militaristic Washington may reverberate in Canada, forcing Prime Minister Justin Trudeau's leadership to make tough decisions with the overall goal of keeping our closest ally happy.

This November, if conventional wisdom holds, Hillary Clinton will be elected president, ushering in a different kind of foreign policy than Barrack Obama, who opted for the unconventional -- a drone war strategy, complimented by strategic special ops deployments like the one that was used to kill Osama bin Laden. Obama is not without his own controversies, including an Orwellian assassination policy legalizing the killing of American citizens at his personal discretion. Still, his administration opted to forgo the traditional invasion tactics America used In Iraq and Afghanistan.

Despite Obama's mistakes, and there were many, his approach probably resulted in less civilian deaths than the traditional American strategy of mobilizing brigades and overwhelming the enemy on the ground. He also stressed the importance of intelligence in the fight against terrorism as a more effective tool than sending in the army.

But what would a Hillary Clinton administration look like, and how will it differ from Obama's eight years in office? If her time as Secretary of State is an accurate barometer, Clinton will be a far more militant commander-in-chief than her predecessor. In fact, it won't even be close.

On several occasions, Obama and Clinton were at opposite ends of American exceptionalism. Obama's approach was to employ a steady-yet-limited type of foreign policy, one that wouldn't be seen as overly hegemonic by more formidable states like China or Russia. But at the State Department, Clinton mostly sided with the four-star generals who were consistent in pressing Obama to increase troop numbers in Afghanistan and arm militant factions in Syria. Even Republicans were amazed at how much farther to the right she was than some of their own military advisers.

The reality of a more militaristic Washington under Clinton may reverberate in Canada, forcing Prime Minister Justin Trudeau's leadership to make tough decisions with the overall goal of keeping our closest ally happy. The juxtaposition of a president seen as a progressive but with the instincts of a conservative hawk will be tough to navigate, putting Trudeau's nice guy image to the test.

Forcing Trudeau to abandon his progressive image might be easier than expected.

The Trudeau Government recently reallocated defence spending towards a renewal of the peacekeeping initiatives Canada was once known for, but the world is now a different place, where peacekeeping and peacemaking are often interchangeable.

A Clintonian foreign policy means Canada will have to choose between its sovereignty and its loyalty to its closest ally and number one trading partner, both of which can come under duress if Trudeau refuses to, say, put boots on the ground in the Middle East. Clinton could also press her military adventures through NATO, forcing Canada to join a fight it may have otherwise declined. Trudeau, who has already shown a tendency to embark on unpopular policies in a quieter manner, or hidden behind calculated photo-ops, will find it far more difficult to convince Canadians that putting troops in harm's way at America's behest is what's best for the nation.

The smart money would be on Trudeau attempting to execute a delicate balancing act between how he characterizes our military involvement and our operational realities. In other words, Trudeau will imitate the same strategy Stephen Harper used when Canada joined the fight against ISIS, when opposition leaders, including Trudeau himself, lobbed accusations of mission creep and a lack of full disclosure.

While the Harper government was accustomed to retreating back to boilerplate responses when faced with opposition inquiries, Trudeau and his ministers will have to craft their responses more carefully as to remain consistent with the "we are a different kind of government" tone that helped them win the election last October.