In the case described by the video in the first link above, US forces stood aside and refused to help Shia under attack for a period covering several weeks. A horrific bout of killings then occurred. Young Ibrahim Sa'ad Al-Jabouri was made to stand and watch his family murdered. The Mayor desparately sought US help only to be denied it. Eventually he was forced to seek help from Iranian militia but that didn't either didn't help or came too late. This pattern is being repeated across large parts of the country. In the US attention focuses only on devising an exit strategy.
Tom Ricks, The Washington Post's military correspondent, opposes the war but strongly opposes a precipitous US withdrawal:
In March 2003 he thought the invasion was a strategic mistake in the struggle against terrorism. His assessment of subsequent events is the title of his book, coming in September: Fiasco.This is sensible. Substantial investment now needs to be made in restoring civil order in Iraq. Indeed even ignoring strategic considerations, attention should focus on ameliorating the miserable lives ordinary Iraqis are now experiencing. Blog accounts of daily life in Bhagdad are here. They are horrifying, real.
Now, however, he thinks that a U.S. withdrawal would leave chaos that might lead to radical Islamists acquiring what they most want — Saudi oil fields and Pakistani nuclear weapons. So America, he thinks, needs a plan to reduce fatalities to two or three a week, then two or three a month.