BRUSSELS—Prime Minister Justin Trudeau is in Brussels today for a meeting of the North Atlantic Treaty Organization and then a Canada-EU summit. Trudeau began his day by meeting with the president of Latvia, where the Canadian military is leading a NATO alliance battlegroup whose mission is to deter Russian aggression in the region. The prime minister then sat down with NATO Secretary General Jens Stoltenberg in a room in front of a photo of the NATO building and Canadian and U.N. flags. Stoltenberg said NATO is entering a new chapter and Canada has always been a defender of the North American alliance with Europe. He thanked Canada for its participation in NATO missions in Latvia and for deciding to have a “centre of excellence” for climate change, which he noted is an issue that affects security. Trudeau also spoke briefly, saying it’s been an “interesting” few years for NATO, and …