LONDON (AP) — Seven British Royal Marines have been arrested on suspicion of murder — an unusual case that could cause a backlash from Afghans and further erode efforts to provide political stability to Afghanistan.

The arrests relate to an incident in Afghanistan last year, and the Defense Ministry said it involved an insurgent rather than a civilian. It comes at a time when relations between NATO forces and the Afghan government are at a low ebb, as they attempt to quash the resilient Taliban insurgency after more than a dozen years of war.