Most of the American soldiers were intimately involved in training Iraqi forces before, too. “When I left in 2009,” Major Modlin said, “they had it, they really did. I don’t know what happened after that.”

“We used to say that every deployment was different,” Major Modlin said. “But we quickly found out that this time was completely different from any other time. The Iraqis know that this time we’re not going to do it for them, and they appreciate that.”

The 300 American soldiers here, with a smaller number of United States Marines at Al Asad air base in Anbar Province, are the only American soldiers deployed outside Baghdad. But as the military sees it, they do not count as “boots on the ground” since their role is purely to train, advise and assist, as part of a 3,000-person deployment authorized in November by President Obama.

In fact, Master Sgt. Mike Lavigne, a military spokesman (one tour in Iraq and three in Afghanistan), does not like that term at all. “We do not have a single boot on the ground,” he said. “Really, not one.”

Even in a training role, however, this venerable Iraqi military base puts American soldiers very close to what passes for a front line in the conflict with the Islamic State, also known as ISIS or ISIL. From time to time, the extremists lob mortar rounds from their hiding places east of the base, just across the Tigris River.

There is little chance they will hit anything. The base is huge, and their aim is as bad as it was in Al Qaeda’s day, when the Americans were last here — and used it as a major training base. Nonetheless, no one goes around without body armor on.