The Islamic State of Iraq and al
Sham (ISIS) is not the only violent group opposed to the government of Iraq.
Groups ranging from Salafist-jihadist to Sunni nationalist have also been
mobilized against Baghdad since at least 2013. They remain a threat to the
government even if ISIS is removed, especially if the core concerns of Iraqi
Sunnis remain unaddressed by the Iraqi government. The primary grievances of
most Iraqi Sunnis include the integration of Shi‘a militias into the Iraqi
Security Forces (ISF), attacks by the ISF in Sunni civilian areas, and
political exclusion in Baghdad.
Some of these groups,
particularly the General Military Council of Iraqi Revolutionaries (GMCIR),
have cooperated with ISIS in its campaign to expel the ISF from parts of Iraq.
Nevertheless, most of them do not share ISIS’s long-term objectives for Iraq.
Each group has come into direct confrontation with ISIS in 2014. Some of these
groups may turn and fight ISIS, but the Iraqi government will not find them an
acceptable partner because they oppose the Shi’a government in Baghdad. In
fact, where ISIS is degraded by military action, these groups may seek to fill
the vacuum and continue to challenge the ISF for control of Iraq’s Sunni
heartland. 
 These groups vary in capability.
Not every group is capable of mounting effective attacks, and not every group
maintains widespread influence. Among the most capable are the General Military
Council of Iraqi Revolutionaries, which is Ba‘athist aligned, and Ansar
al-Islam. Both groups represent long-term threats to the Iraqi state. Even the
smaller groups, though, disrupt ISF operations and make them vulnerable to
better-equipped groups like the GMCIR, Ansar al-Islam, and ISIS. Should the
Iraqi Security Forces launch ground assaults into Sunni areas that are
currently under ISIS’s control, they will likely meet with armed resistance by
these groups, which will likely prioritize the fight against the Iraqi state
over the fight against ISIS. 
 The success of a ground war against ISIS in
Iraq depends upon the Sunni population. This population, mostly behind the ISIS
control line, is more proximate to the influence of ISIS and Sunni insurgent
groups than to the Iraqi state or the U.S.-led counter-ISIS coalition. A
strategy to destroy ISIS requires that these competing influences be outmatched
to such a degree that the Sunni population once more decides to side with the
Iraqi government to fight ISIS on behalf of the state. This will likely
be the most difficult requirement for the counter-ISIS campaign. 
 Lack of national-level Sunni
leadership feeds support for local insurgent groups. Many Sunni political
leaders on the national stage lost credibility with the population during the
protest movement, during which a number sought political accommodations with
the Maliki government. Many of these national figures no longer effectively
represent the Sunni population, as the 2014 parliamentary elections
demonstrated. Inclusion of these national figures will not likely bring the
wider Sunni population behind the government in Baghdad.  Rather, a
political accommodation in Baghdad that appeals to Iraq’s Sunni population is
essential in order to mend this critical vulnerability of the Iraqi state
permanently. Without this, the Sunni population will more likely oppose than
welcome an Iraqi-led military campaign to retake Iraq’s cities from ISIS.
Presently, the Sunni population living under ISIS control is disconnected from
Sunni national politics, and this separation must also be overcome in order for
Iraq to survive. A military campaign to destroy ISIS that does not treat this
condition will accelerate Iraq’s descent into a sectarian civil war. 
- See more at:
http://www.understandingwar.org/report/beyond-islamic-state-iraqs-sunni-insurgency#sthash.z6Ajmf85.dpuf
The
 Islamic State of Iraq and al Sham (ISIS) is not the only violent group 
opposed to the government of Iraq. Groups ranging from Salafist-jihadist
 to Sunni nationalist have also been mobilized against Baghdad since at 
least 2013. They remain a threat to the government even if ISIS is 
removed, especially if the core concerns of Iraqi Sunnis remain 
unaddressed by the Iraqi government. The primary grievances of most 
Iraqi Sunnis include the integration of Shi‘a militias into the Iraqi 
Security Forces (ISF), attacks by the ISF in Sunni civilian areas, and 
political exclusion in Baghdad. 
This anti-government mobilization 
developed months before the fall of Mosul to ISIS in June 2014. Most of 
the current anti-government groups had been active during the Sunni 
insurgency following the fall of Saddam Hussein. The militancy of these 
groups and their prominence declined as Sunni political participation 
increased in 2009 and 2010.  After the U.S. withdrawal in 2011, Maliki’s
 political marginalization of Sunni leaders and sectarian command of the
 Iraqi Security Forces spurred an anti-government protest movement, 
primarily in Sunni areas such as Anbar and Salah ad-Din. The protest 
movements spawned an organized, overt militant opposition to the Iraqi 
government after the Iraqi Security Forces killed civilians while 
attempting to clear a protest camp in Hawija in April 2013.  The armed 
Sunni rebellion fostered the conditions in Fallujah and Mosul that ISIS 
exploited to capture the cities in January and June 2014, respectively.  
Some of these groups, particularly the
 General Military Council of Iraqi Revolutionaries (GMCIR), have 
cooperated with ISIS in its campaign to expel the ISF from parts of 
Iraq. Nevertheless, most of them do not share ISIS’s long-term 
objectives for Iraq. Each group has come into direct confrontation with 
ISIS in 2014. Some of these groups may turn and fight ISIS, but the 
Iraqi government will not find them an acceptable partner because they 
oppose the Shi’a government in Baghdad. In fact, where ISIS is degraded 
by military action, these groups may seek to fill the vacuum and 
continue to challenge the ISF for control of Iraq’s Sunni heartland. 
These groups vary in capability. Not 
every group is capable of mounting effective attacks, and not every 
group maintains widespread influence. Among the most capable are the 
General Military Council of Iraqi Revolutionaries, which is Ba‘athist 
aligned, and Ansar al-Islam. Both groups represent long-term threats to 
the Iraqi state. Even the smaller groups, though, disrupt ISF operations
 and make them vulnerable to better-equipped groups like the GMCIR, 
Ansar al-Islam, and ISIS. Should the Iraqi Security Forces launch ground
 assaults into Sunni areas that are currently under ISIS’s control, they
 will likely meet with armed resistance by these groups, which will 
likely prioritize the fight against the Iraqi state over the fight 
against ISIS. 
The success of a ground war against 
ISIS in Iraq depends upon the Sunni population. This population, mostly 
behind the ISIS control line, is more proximate to the influence of ISIS
 and Sunni insurgent groups than to the Iraqi state or the U.S.-led 
counter-ISIS coalition. A strategy to destroy ISIS requires that these 
competing influences be outmatched to such a degree that the Sunni 
population once more decides to side with the Iraqi government to fight 
ISIS on behalf of the state. This will likely be the most difficult 
requirement for the counter-ISIS campaign. 
Lack of national-level Sunni 
leadership feeds support for local insurgent groups. Many Sunni 
political leaders on the national stage lost credibility with the 
population during the protest movement, during which a number sought 
political accommodations with the Maliki government. Many of these 
national figures no longer effectively represent the Sunni population, 
as the 2014 parliamentary elections demonstrated. Inclusion of these 
national figures will not likely bring the wider Sunni population behind
 the government in Baghdad.  Rather, a political accommodation in 
Baghdad that appeals to Iraq’s Sunni population is essential in order to
 mend this critical vulnerability of the Iraqi state permanently. 
Without this, the Sunni population will more likely oppose than welcome 
an Iraqi-led military campaign to retake Iraq’s cities from ISIS. 
Presently, the Sunni population living under ISIS control is 
disconnected from Sunni national politics, and this separation must also
 be overcome in order for Iraq to survive. A military campaign to 
destroy ISIS that does not treat this condition will accelerate Iraq’s 
descent into a sectarian civil war.