2005, with 102 Americans killed. Total attacks in
October 2006 averaged 180 per day, up from 70 per day in January 2006.
Daily attacks against Iraqi security forces in October were more than
double the level in January. Attacks against civilians in October were
four times higher than in January. Some 3,000 Iraqi civilians are
killed every month.

Sources of Violence

Violence is increasing in scope, complexity, and lethality. There are
multiple sources of violence in Iraq: the Sunni Arab insurgency, al
Qaeda and affiliated jihadist groups, Shiite militias and death
squads, and organized criminality. Sectarian violence--particularly in
and around Baghdad--has become the principal challenge to stability.

Most attacks on Americans still come from the Sunni Arab insurgency.
The insurgency comprises former elements of the Saddam Hussein regime,
disaffected Sunni Arab Iraqis, and common criminals. It has
significant support within the Sunni Arab community. The insurgency
has no single leadership but is a network of networks. It benefits
from participants' detailed knowledge of Iraq's infrastructure, and
arms and financing are supplied primarily from within Iraq. The
insurgents have different goals, although nearly all oppose the
presence of U.S. forces in Iraq. Most wish to restore Sunni Arab rule
in the country. Some aim at winning local power and control.

Al Qaeda is responsible for a small portion of the violence in Iraq,
but that includes some of the more spectacular acts: suicide attacks,
large truck bombs, and attacks on significant religious or political
targets. Al Qaeda in Iraq is now largely Iraqi-run and composed of
Sunni Arabs. Foreign fighters--numbering an estimated 1,300--play a
supporting role or carry out suicide operations. Al Qaeda's goals
include instigating a wider sectarian war between Iraq's Sunni and
Shia, and driving the United States out of Iraq.

Sectarian violence causes the largest number of Iraqi civilian
casualties. Iraq is in the grip of a deadly cycle: Sunni insurgent
attacks spark large-scale Shia reprisals, and vice versa. Groups of
Iraqis are often found bound and executed, their bodies dumped in
rivers or fields. The perception of unchecked violence emboldens
militias, shakes confidence in the government, and leads Iraqis to
flee to places where their sect is the majority and where they feel
they are in less danger. In some parts of Iraq--notably in
Baghdad--sectarian cleansin