Gradually, as it became clear that Iraq was in the midst of a protracted guerrilla war, the U.S. military rejected the title "resistance," with its connotations of legitimacy, and settled on "insurgents" or "terrorists" as operative labels.
But the evolving nature of the battle has thrown those terms into question too.
"The core conflict in Iraq [has] changed into a struggle between Sunni and Shia extremists," the Pentagon wrote in an unusually frank report to Congress last month. "Death squads and terrorists are locked in mutually reinforcing cycles of sectarian strife."
Trained and equipped by the U.S. government, Iraq's security forces have been infiltrated by thousands of militiamen loyal to Shiite clerics and factions. There is widespread agreement among military commanders that Shiite militiamen are behind most death squad killings.
The term "death squad" entered public discourse during the dirty wars in Central America to describe clandestine assassins who often plied their trade with the tacit approval of government authorities in the region. But the issue of Shiite death squads is an extremely touchy one for the U.S.-backed, Shiite-dominated government.
Members of the fiercest death squad are allegedly recruited from the Al Mahdi militia, a group under the command of Muqtada Sadr, a virulently anti-U.S. cleric whose supporters are key players in the ruling coalition of Prime Minister Nouri Maliki.
U.S. officials were reluctant to use the term until July, when Gen. George W. Casey Jr., the top military commander here, and U.S. Ambassador Zalmay Khalilzad issued a joint statement condemning "in the strongest possible language the recent attacks by terrorists and death squads against innocent Iraqi civilians."
The following day, Caldwell used the term repeatedly when speaking with reporters -- but he applied the term to both Sunni and Shiite Arab groups.
"We're really not boring in on what organization they're from," said Col. Michael Shields, commander of the Army's 172nd Stryker Brigade Combat Team.
By unmooring death squads from the context of government-backed Shiite militias, U.S. officials have redefined the problem -- and avoided a direct confrontation with the U.S.-backed Iraqi leadership.
Like their U.S. colleagues, Iraqi authorities have demonstrated an adroitness with numbers, terms and dates.
