In developing Canada's new defence strategy, the federal government faces the pressure of events and some fundamental constraints.The first and most challenging constraint is budgetary. Budgets are to strategy what teeth are to lips.The Speech from the Throne promised investment in a “leaner, more agile, better-equipped military.” It will certainly be leaner, given competing pressures around other government priorities, including infrastructure, indigenous peoples, climate-change mitigation and health care.As it addresses its budgetary challenges, the government also needs to get a grip on military procurement.Our F-35 purchase, originally estimated at $75 million apiece, was to be 65 planes, but as the costs ballooned to $45-billion from $9-billion, the previous Conservative government hit the reset button. Meanwhile, the Norwegians are buying 52, the Australians 72 and the British 138. For its part, the Liberal government has launched an “open and transparent competition letter ” to replace our aging CF-18s.The cost of Canada's new navy fleet is also rising. The cost for the originally proposed 15 new frigates, six to eight Arctic offshore patrol ships, two joint supply ships and Coast Guard vessels, including the icebreaker CCGS John Diefenbaker, is probably double the originally estimate of $38-billion. By comparison, Australia recently committed $90-billion to its shipbuilding program for eight new frigates and 20 new patrol ships.The second constraint is the messy, confusing and constantly evolving international environment. (A useful Canadian perspective is the just released Conference of Defence Associations Institute's annual Strategic Outlook: In Search of a New Compass.)The third constraint is defining defence priorities. While the government shares some priorities with the Conservative government before it, it is also renewing commitments to traditional Liberal approaches such as a renewed focus on peacekeeping.The Conservative government's “Canada First” defence strategy prioritized homeland defence and specifically the Arctic. The second priority was defence of North America and participation in the North American Aerospace Defence Command, which for the Liberal government also means a reconsideration of ballistic missile defence in the wake of North Korean missile tests. Its third priority was our collective security obligations through the North Atlantic Treaty Organization and supporting international peace and security.These commitments are all reflected in Defence Minister Harjit Sajjan's mandate letter, along with protecting vital infrastructure from cyber-threats; a workplace free from harassment and discrimination; a suicide-prevention strategy, and creating better synergies with the Veterans Affairs Department.And last week, Prime Minister Justin Trudeau told United Nations Secretary-General Ban Ki-moon that his government is also renewing Canada's UN peace-operations commitments.The government's initial assessment of our defence priorities is correct. Not surprisingly, there is a lot of continuity with those of the previous Conservative government.The Arctic, in particular, needs more attention. Claiming sovereignty in the Arctic is easy. Exercising it requires more than the government's promise to increase the approximately 5,000 Canadian Rangers.Russia and Canada have both staked claims to the North Pole. But the Russians are backing their claims with military might: Last year saw their largest ever northern war games, involving more than 35,000 troops, 50 ships and submarines and 110 aircraft. The Russians have 42 icebreakers and well-developed Arctic ports.In defending our North, polling indicates that Canadians are prepared to take a firm line “regardless of the cost.” For now, Canada has two heavy icebreakers. We need more icebreakers and surveillance aircraft and we need to complete theas-yet-unfinished permanent northern base in Nanisivik, Nunavut, that the Conservative government promised.The lack of real action in the Arctic is illustrative of a fourth constraint: leadership.Fair or not, ceasing the combat role in Iraq raises new doubts about Mr. Trudeau's resolve on defence. Having agonized through many months over an Afghan strategy, U.S. President Barack Obama will empathize with Mr. Trudeau's decision. But others will be reminded of Jean Chrétien's refusal to join the ill-fated Iraq invasion, Pierre Trudeau's “peacenik” crusade, Lester Pearson's criticism of the Vietnam War or John Diefenbaker's lack of early and unequivocal support for the Americans during the Cuban missile crisis.History has vindicated the Canadian approach (Mr. Diefenbaker excepted). And Canadians need no persuading about the value of security, but they do look for leadership and vision.To that end, the government's defence review must involve public outreach and parliamentary debate that inform and educate Canadians on why we have a navy, air force and army. Decisions on force levels should be made only after looking all three legs of the defence stool:· Readiness: How quickly can we get the job done?· Capability: How much of an edge do we have over potential adversaries?· Capacity: Do we have the numbers to meet the challenges?For now, we continue to do defence on the cheap, free-riding under the U.S. security umbrella and spending just 1 per cent of gross domestic product on defence, the least of any member of the Arctic Council, and significantly less than Australia (1.8 per cent), France (1.8 per cent), Britain (2.07 per cent) and the United States (3.07 per cent).For the world to acknowledge that “Canada is back,” we need to put our money where our mouth is: It's time to increase our defence insurance premiums.This item first appeared in the Globe and Mail on Feb. 18, 2016.