Less than 24 hours after President Muhammadu Buhari departed Cameroon at the end of a two-day visit, the country has expelled 2,000 Nigerians. Those affected were said to be living in the country without permit. They were arrested on Thursday in Kousseri, northern Cameroon, and loaded into many trucks, then driven across the border into Nigeria. A local administrator in Kousseri said the raid was part of measures aimed at improving security and controlling movements along the border region. Most of the deportees are among the 40, 000 Nigerian refugees who fled as a result of the insurgency in the north-east. Buhari and President Paul Biya have pledged to work together to crush the six-year violence, which has killed thousands and spread to neighbouring countries, threatening the stability of the Lake Chad region.