HMCS Charlottetown is sailing to the coast of Libya, and no one knows when she'll be back.
Her job - on a mission that could last as long as six months - is to be a platform for Canada as the government moves along a sliding scale of progressively more difficult decisions on involvement in Libya, but also to be there for the next crisis, if there is one.
Canada doesn't often dispatch warships to respond to political crises, so the Charlottetown is a symbol the Harper government wants to shed the sense it has reacted overcautiously to unrest in the region.
For Mr. Harper, facing a Canadian public relieved that combat troops are returning from Afghanistan but outraged by events in Libya, there is a balance to strike: to take an active role in the crisis, while not being first with public calls for more direct military intervention.
The Harper modus operandi is to focus public attention on immediate steps, and not to speak on the world stage with grand calls for action that Canada can't back up. There's a will to play a role with the military, and now a series of calculations about the military's role.
There will be evacuation missions. Then there will be humanitarian ones, likely headed into eastern regions of Libya now held by the opposition, which effectively means delivering support to one side in a civil war.
Then there is more direct military action. There's no appetite for sending ground troops, apart from special forces now involved in evacuation missions. But the government has signalled its willingness to take part in an international naval blockade, and in behind-the-scenes diplomatic discussions in places like NATO is siding with the U.S. and British position that allies should make plans for a no-fly zone.
At the moment, that's on hold. The military cargo planes and reconnaissance and liaison teams based in Malta are still focused on evacuations. But they and especially the Charlottetown, expected to arrive in 10 to 12 days, can also be used for aid.
Mr. Harper announced $5-million in humanitarian aid to Libya on Wednesday, and Canada is likely to contribute more toward evacuating refugees on Libya's borders, mostly Egyptians.
The Charlottetown, according to current plans, is expected to load supplies in Europe for aid missions to eastern Libya, effectively delivering support to areas under opposition control.
That's also part of the political struggle aimed at hemming Mr. Gadhafi in. Aid won't be seen as Western aggression, and will bring more outside presence and attention to rebel-held areas, which some hope might discourage massive attacks.
A similar calculation about the politics of intervention is involved in imposing a no-fly zone, and it's likely to govern Canada's involvement.
Enforcing a no-fly zone would probably require bombing Libyan defences, a step few countries are willing to take for fear it could backfire. Within NATO, France and Italy are cool to a no-fly zone, while the United States and Britain have argued that allies must plan it, essentially making it a threat Mr. Gadhafi will have to consider.
Canada, according to government sources, sides with the U.S.-British position, but the government hasn't made public calls for it in part because it doesn't have the military power to enforce it - it is thought taking that position too quickly, and alone, would lack credibility.
A no-fly zone is unlikely to happen without an international mandate, but that's not likely to come from the United Nations, where Russia and China dislike giving Western powers a mandate to intervene in a civil war. It's more likely to come from NATO, raising the fear it will be portrayed as another Western intervention in an Arab nation. Canada would like a NATO mandate that comes with involvement from an Arab nation - and any NATO mandate will require at least the acceptance of allies like Italy and France.
That means threading a needle for a Canadian public that typically wants a part in an international response, and diplomatic efforts to take the pulse of not just the lead players, but middle powers like Australia, Germany and Japan.
But the calculations will all change rapidly if Mr. Gadfhafi turns to widespread bombing of Libyans, raising the spectre of mass killings that could pressure countries to support the no-fly zone, at least within NATO. And many think Ottawa would be unlikely to turn down the United States and Britain if they come calling for a small Canadian contribution, like half a dozen CF-18 fighters. "If asked, I believe Canada's response would be positive," said Conservative Senator Hugh Segal.
There is another reason why a frigate that will take 10 days to reach the region has been dispatched, and might be there for a while. After three crises in the region, another in Syria or Jordan could mean thousands of Canadians to evacuate, not hundreds. Inside the government, the military missions for the Libyan crisis are part of the contingency plan for a next one.
Campbell Clark writes on foreign affairs from Ottawa