Defense Secretary Ashton Carter explained the administration's vision when he testified last month before the Senate Armed Services Committee.
"What happened last year was an unwillingness of the Iraqi security forces to fight, using the equipment and training that the United States had given them," Carter told the committee. "And the reason for that was a political failure on the part of their government to keep the promise that had been made to the country to keep it a multisectarian state. And that was not what was happening under (former Iraqi Prime Minister Nouri) al-Maliki, and that's the reason why the forces folded."
Because of this, as described by Carter, the U.S. must now focus on what he called a "political thing."
"So the most important thing we can do going forward is to make sure that Iraq doesn't decline again into sectarianism," he said. "And so that's the most important thing we can do, and it's a political thing, rather than a technical thing involving the training, but it's job one."
Carter could not stress enough that multisectarianism is the administration's goal in Iraq.
"Our approach to combating ISIL in Iraq is to work with the Iraqi security forces and a multisectarian government that takes a multisectarian approach to defeating ISIL and regaining control of its own territory," he testified.
"So we need to have success against ISIL, but we need to have it in a way that doesn't inflame sectarianism again," he said.
"Sectarianism is what brought us to the point where we are," he said.
Carter was not talking about conflict among Iraq's terrorized and dwindling Christian denominations, but between Sunni Muslims and Shia Muslims.
This conflict between Iraqi Sunnis and Shia -- with the group that was then called al-Qaida in Iraq (now ISIL) at the center of it -- was central to U.S. security concerns for Iraq in the immediate aftermath of President Obama's withdrawal of the last U.S. forces from that country at the end of 2011.
"But we're leaving behind a sovereign, stable and self-reliant Iraq with a representative government that was elected by its people," Obama said in a Dec. 14, 2011, speech at Fort Bragg.
"This is an extraordinary achievement, nearly nine years in the making," Obama said.
As this column noted last week, the group the administration now calls ISIL existed before the 2003 invasion of Iraq and survived the eight-year U.S. occupation of that country.
Just six weeks after Obama announced he was leaving behind a "sovereign, stable and self-reliant Iraq," Director of National Intelligence James Clapper implicitly conceded in a Worldwide Threat Assessment presented to the Senate Select Committee on Intelligence that a sectarian war was continuing at that very moment in Iraq and that the group the administration now calls ISIL was at the center of it.
"We assess that AQI will remain focused on overthrowing the Shia-led government in Baghdad in favor of a Sunni-led Islamic caliphate," Clapper testified on Jan. 31, 2012. "It probably will attempt attacks primarily on local Iraqi targets, including government institutions, Iraqi security forces personnel, Shia civilians and recalcitrant Sunnis, such as members of the Sons of Iraq, and will seek to rebuild support among the Sunni population. In its public statements, the group also supports the goals of the global jihad, and we are watchful for indications that AQI aspires to conduct attacks in the West."
Three years later, with AQI having changed its name to Islamic State and having taken control of regions in Iraq, Syria and Libya, Lt. Gen. Vincent Stewart, director of the Defense Intelligence Agency, suggested the group's success was dependent on the attitude of the Arab Sunni populations in the areas it had seized.
"We expect ISIL to continue entrenching itself and consolidating gains in Sunni areas of Iraq and Syria while also fighting for territory outside those areas," he said in DIA's 2015 Worldwide Threat Assessment.
"Seizing and holding Shia- and Kurdish-populated areas of Iraq have been and will continue to be difficult for ISIL in 2015," he stated.
"ISIL's ability to govern the areas it has captured in Iraq and Syria, and its ability to keep the support -- or at least acquiescence -- of the Sunni population will be key indicators of the success or failure of the self-declared 'Islamic state,'" he said.
This, then, is the essence of the "political thing" Carter cited in his testimony: getting Iraqi Sunnis in regions controlled by the Islamic State to switch their "support" or "at least acquiescence" to a government in Baghdad that is not dominated by Sunnis.