By JOSH BOAK and ROB GILLIES (Associated Press) OTTAWA, Ontario (AP) — President Joe Biden arrives in Canada on Thursday with a focus on several of the world’s largest challenges: the war in Ukraine, climate change, trade, mass migration and an increasingly assertive China. Two important areas of agreement appear in hand: Canada will escalate its timeline for military upgrades to the North American Aerospace Defense Command and the two nations will reach an agreement on migration, a senior Canadian official told The Associated Press. The Biden administration has made strengthening its friendship with Canada a priority over the past two years and Biden’s meetings with Canadian Prime Minister Justin Trudeau in the capital of Ottawa are an opportunity to set plans for the future. National security and air defenses are a priority, with a recent Chinese spy balloon floating over North America putting newfound urgency on Canada’s plans to update its radar systems and recent purchase of F-35 jets.