OTTAWA -- When Harjit Singh Sajjan went to join the Canadian military 26 years ago, he was rejected by the first unit where he applied.

But he stuck it out -- and now the retired reserve lieutenant-colonel, a veteran of three combat tours in Afghanistan, finds himself running the place.

Sajjan was sworn in Wednesday as Canada's new minister of defence, leapfrogging retired lieutenant-general and star Liberal candidate Andrew Leslie -- Justin Trudeau's foreign affairs and defence adviser before last month's federal election.

In addition, Sajjan will sit on some of the new government's most powerful cabinet committees, including public safety and intelligence, which dovetails not only with his wartime experience, but also the 11 years he spent battling gangs as a Vancouver cop.

But if there ever was a proving ground for the complexities and murky choices of Ottawa, it was Kandahar province in 2006, when Sajjan was tasked as the intelligence liaison with notorious governor Asadullah Khalid and Ahmed Wali Karzai, the controversial head of the provincial council.

Khalid, who later became the head of Afghan intelligence, had a reputation for ruthlessness and was accused of assassinations, torture and drug-dealing. Karzai, the half-brother of the former president who was later murdered by a bodyguard, was accused of having a hand in the drug trade.

"Nobody should under-estimate Harjit," said retired major-general Dave Fraser, who gave Sajjan the job of dealing with the volatile Afghan power brokers at a time when the Taliban were on the offensive and Canadian casualties were on the rise.

"Some people in Ottawa are going to want to pick on him because he's new, but let me tell you, he is tough and smart, and determined."

Sajjan's determination to serve in the face of the blatant racism he faced when he first joined speaks volumes about his character, Fraser added.

The Afghans had an affinity for Sajjan, a Sikh, because they believed he understood their struggle to be respected in the West, said Fraser, recalling how the pair hit it off over tea at the governor's palace.

In his official biography, the Liberals focus on Sajjan's medals and his time as the first Sikh regimental commander in the Canadian Army. Fraser prefers to describe him as a "true warrior," someone who thrives in the face of adversity.

"I'm a fan and I admit it," said Fraser, who was in charge of NATO's southern Afghan command during the difficult, bloody early months of the Kandahar campaign.

"I picked him because of his experience in dealing with gangs because the Taliban were nothing more than a bunch of thugs and gangs."

His only advice for his former subordinate is not to make the same mistake as Gordon O'Connor -- Stephen Harper's first defence minister -- who tried to run the military as well as the Department of National Defence.

"He has an immensely capable chief in (Gen.) Jon Vance. He should concentrate on policy," and straightening out the tangled mess that is the defence procurement file, Fraser said.

Some of the new government's hottest files will land on his desk, including the Liberal pledge to end the bombing campaign against militants in Iraq and Syria and possibly the promised transition to a beefed-up training mission.

Either Trudeau or Sajjan should have a serious conversation with the Americans about the overall direction of the war before committing additional troops to training, said retired colonel George Petrolekas of the Conference of Defence Associations Institute.

One of the thorny questions Sajjan will grapple with is whether Canada sticks with training Kurdish peshmerga fighters, or wades into the murky Shia-Sunni sectarian divide within the Iraqi military.

The other immediate consideration will be fulfilling the Liberal pledge to replace the country's CF-18 fighter fleet with something other than the F-35, which the air force has been lobbying for since 2006.