As marines aboard fast patrol boats roared up the Euphrates on a dawn raid on Sunday, images pressed in of another American war where troops moved up wide rivers on camouflaged boats, with machine-gunners nervously scanning riverbanks for the hidden enemy.
That war is rarely mentioned among the American troops in Iraq, many of whom were not yet born when the last American combat units withdrew from Vietnam more than 30 years ago. A war that America did not win is considered a bad talisman among those men and women, who privately admit to fears that this war could be lost.
But as an orange moon sank below the bulrushes on Sunday morning, thoughts of Vietnam were hard to avoid.
Marines waded ashore through soft silted mud that caused some to sink to their waists, M-16 rifles held skyward as others on solid land held out their rifle barrels as lifelines.
Ashore, sodden and with boots squelching mud, the troops began a five-hour tramp through dense palm groves and across paddies crisscrossed by deep irrigation canals.
There were snatches of dialogue from "Apocalypse Now," and a black joke from one marine about the landscape resembling "a Vietnam theme park."
But behind the joshing lay something more serious: the sense expressed by many of the Americans as they scoured the area that in this war, too, the insurgents might have advantages that could make them a match for highly trained troops, technological gadgetry and multibillion-dollar war budgets.
The 24th Marine Expeditionary Unit conducted the river raid as part of a weeklong offensive billed as a sequel to the battle for Falluja, less than 20 miles upriver from the village where the marines landed Sunday.
The 40-foot river craft they used are called Surcs, for Small Unit Riverine Craft, a high-tech update on the Swift boats used in Vietnam. The craft were flown into Iraq aboard giant C-5 transport aircraft and were first deployed with five-man crews during the battle for Falluja this month, patrolling the stretch of the Euphrates that runs along the city's western edge to prevent attempts by insurgents to escape that way after American troops had thrown a cordon around the city.
Those patrols were judged a success by American commanders. Now they are eager to exploit the potential the patrol boats give them for mounting fast, unexpected attacks along the Tigris and the Euphrates. The rivers run through many of the cities and towns that are rebel strongholds, and the long stretches of verdant riverbank provide ideal hiding places for insurgents and their weapons caches.
Somewhere Jon O'Neill's distilled ears just burned.