SOFIA CHRISTENSEN AT least 50 civilians were killed during a military operation conducted by Mali's army and "foreign troops" on April 19, the United Nations said in a report. The U.N. has repeatedly accused Malian soldiers of summarily executing civilians and suspected militants over the course of their decade-long fight against groups linked to al Qaeda and Islamic State. Mali's military government, which took power in a 2020 coup, has been battling Islamist insurgents with the help of private military contractors belonging to Russia's Wagner group. The alleged April massacre took place on market day in Hombori municipality, in the…