sentences:  Even in 2006 and 
  2007, the new Iraqi governments, installed in June 2004 and May 2006 and supported by U.S. and British forces, were still facing strong domestic and terrorist opposition, from groups whose identity was not always certain.Islamic State of Iraq (ISI) was a Sunni Islamic militant group that in 2003–2004, under an earlier name, had chosen as killing targets Shia Islamic mosques and civilians, Iraqi government institutions, and the U.S.-led Multi-National Force in Iraq.The U.S. 4th Battalion, 31st Infantry Regiment, 2nd Brigade, 10th Mountain Division, arrived in Iraq in September 2006, had until May 2007 already lost 18 of its members killed in action, and was living in Iraq under hard conditions, when it was, in May 2007, charged with a military observation post outside Mahmudiyah in the notoriously dangerous area known as the Triangle of Death, south of Baghdad.