There are growing signs of hostility between secular Iraqi insurgents and Muslim extremists — some of them foreigners — fighting under the banner of al-Qaida.The factions have exchanged threats and are increasingly divided over the strategy of violence, much of it targeting civilians, that aims undermine the fragile new government. The increased tension, critically, arises as the mainstream component of the Sunni Arab-led insurgency — which remains active, deadly and vibrant nearly two years since it began — has opened a campaign designed to reap political gain out of its violent roots.Full Story