The Libyan army imposed a no fly zone over Benghazi on Saturday in a direct challenge to a retired general who has been using airpower to press a campaign against Islamist militants there.

Khalifa Haftar, who lived in exile in the United States before returning home to lead ground forces in the 2011 NATO-backed uprising that toppled Muammar Gaddafi, heads what he calls a “National Army”.

On Friday his paramilitary force, backed by warplanes and helicopters, pounded Islamist militiamen in Libya’s second city and pitched battles with the ex-rebels. […]