Moscow - Russian troops and police, backed by heavy guns and attack helicopters, unleashed one of their biggest assaults on a Chechen town in months yesterday. The attack on Argun happened as an EU human rights mission flew into the region. Hours before a team of Moscow-based EU ambassadors landed in Chechnya to check on the human rights situation, troops and police swooped moved in on Argun, Chechnya's third-biggest town, to wipe out what the military said were two rebel groups.