OTTAWA—Prime Minister Justin Trudeau says Canada is weighing measures beyond existing sanctions against Belarus after its government forced down an airliner and seized a dissident journalist on board. At a news conference Tuesday, Trudeau is calling the incident “outrageous, illegal and completely unacceptable.” The prime minister says the arrest Sunday of Belarusian journalist Roman Protasevich after his Ryanair flight was intercepted by a Belarusian fighter jet in the country’s airspace amounts to a “clear attack on democracy and freedom of the press.” Trudeau is calling for Protasevich’s immediate release, and says he is considering “further options” regarding the regime. Canada announced sanctions against 55 Belarusian officials last year after an election that Ottawa said was “marred by widespread irregularities” amid a “systemic campaign of repression” and human rights violations under President Alexander Lukashenko. Since Sunday, airlines have rerouted flights to avoid the country’s airspace and European Union leaders have directed …