President Joe Biden arrived in Canada on Thursday for talks with Prime Minister Justin Trudeau on several of the world's most difficult challenges: the war in Ukraine, climate change, trade, mass migration, and an increasingly assertive China.?Two important agreements appeared to be in hand before Biden even departed Washington. Canada will escalate its timeline for military upgrades to the North American Aerospace Defense Command and the two nations have reached an agreement to update rules for migrants seeking asylum, according to U.S. and Canadian officials. The officials were not authorized to comment publicly and requested anonymity.