PARIS—As it pays tribute Thursday to French soldiers killed in Mali and faces questions over a deadly airstrike, France is considering changing its military strategy against Islamic extremists in Africa’s Sahel region—and a possible partial troop pullout. President Emmanuel Macron is expected to announce a timeframe for the evolution of France’s largest international military operation at a summit in Chad’s capital N’Djamena next month. On Thursday afternoon, an elaborate ceremony was held on the Alexandre III bridge in central Paris to pay homage to two soldiers who were killed in Mali by an improvised explosive device that hit their armored vehicle on Saturday. Three other French soldiers died just five days earlier in similar circumstances. France’s operation in Mali is also shadowed by unclear circumstances surrounding a weekend airstrike that killed at least 20 people in a village where witnesses said Islamic extremists had confronted a wedding party. The French …