Libya’s internationally recognized prime minister escaped an assassination attempt, the latest sign of a widening security vacuum that is complicating European Union efforts to stem the flow of illegal migrants from the country. Prime Minister Abdullah al-Thinni was targeted Tuesday night when several unidentified gunmen shot at his motorcade as he left a parliamentary session in the eastern city of Tobruk, according to a member of parliament and security officials. Libya’s internationally recognized government is based in Tobruk while a rival administration opposed to Mr. Thinni is based in the capital Tripoli and controls the country’s west. Human smugglers have exploited Libya’s deep political crisis and insecurity to use the country as a launching ground for thousands of migrants —mostly African and Middle Eastern—making the perilous journey across the Mediterranean Sea. […]