As Islamic militants from Boko Haram step up attacks in Nigeria that have led to the slaughter of more civilians, there is increasing talk that international military action, possibly including a multinational force, may be needed to help crush the insurgency in Africa’s most populous country.

THE crisis over chemical weapons in Syria has underlined a central dilemma for the West as it tries to deal with the country’s civil war — the lack of attractive alternatives to President Bashar Assad.