In January 2013, strewn amid the rubble and debris left after a terrorist attack on a gas plant in the Algerian desert were the remains of two men who had traveled far from home to wage what they viewed as a holy war.

There is no more visible sign that America is putting the Iraq war behind it than the colossal operation to get its stuff out: 20,000 soldiers, nearly a sixth of the force here, assigned to a logistical effort aimed at dismantling some 300 bases and shipping out 1.5 million pieces of equipment, from tanks to coffee makers.

Insurgents detonated bombs and threw grenades on Monday at or near six Iraqi police and army checkpoints, in assaults on the most visible deterrents the Iraqi government has to attacks.

In a coordinated assault on an American combat outpost north of Baghdad on Monday, suicide bombers drove three cars laden with explosives into the base, killing two American soldiers and wounding at least 17 more, according to witnesses and the American military.