Britain's government is facing a legal challenge Thursday over its use of a drone to kill two British Islamic State (IS) group jihadists in Syria, even though it is not part of military action there. Prime Minister David Cameron announced this month that a British drone had killed two British jihadists and another unidentified militant in the group's stronghold of Raqqa in August. That was the first such strike carried out by Britain in a country where it is not at war and prompted fierce criticism from human rights campaigners. Now two leading members of Britain's Green Party and legal...