ISKANDARIYAH, Iraq – The American military’s most critical operation since the capture of Saddam Hussein is putting boat patrols on the Euphrates River, tanks on strategic routes, and warplanes overhead in a mission tens of thousands of troops strong: ensuring a credible, Iraqi-run national election.

The run-up to Sunday’s vote is pressing every available American service member into action in most of Iraq – assisting an Iraqi-ordered nationwide ban on traffic from Saturday to Monday to block car bombs and other attacks on election targets; and preparing to respond to any Iraqi request for help repelling assaults or tending casualties.

The election plan puts the might of the American military in a full-force back-up role. American forces are funneling stepped-up training, hundreds of fixed barricades, and miles of razor wire, weapons, body armor, communication systems, generators, and the fuel to run them, and even water and meals-ready-to-eat rations to Iraqi police and troops charged with the front-line defense of polling sites.

American military medical teams here will stand by on 15-minute alert, and soldiers and Marines have intensified sweeps to try to neutralize insurgents ahead of election day.

What American forces won’t do, America says, is thrust themselves into a role in which Americans, not Iraqis, are seen as conducting Iraq’s first post-Saddam elections, pivotal to opening the way for any cohesive Iraqi statehood and clearing the way out for an eventual American troop withdrawal.

In this tense area just south of Baghdad, that hands-off prime directive translates into a simple command, when voting opens Sunday at 7 a.m.

“Unless someone tells you otherwise, you will have no contact with the ballots,” Lieutenant Colonel Bob Durkin ordered officers of the 24th Marine Expeditionary Unit infantry south of Baghdad, in an election-security planning session.

“They want us to have nothing to do with that, and they’re right,” Colonel Durkin told his officers, gathered around a wall projector in a tent chapel. “It’s their elections.”

Election strategy sessions among Iraqi and American forces are taking place near daily in the so-called triangle of death, against a backdrop of attacks targeting both.

“It’s important to emphasize there’s probably going to be more violence leading up to the elections, we know that,” Colonel Durkin said at one meeting with police chiefs of the Iskandiriyah area, steeling still-wobbly Iraqi security forces the morning after one of their police vehicles rolled across a trip wire here, triggering a blast that killed two of the policemen inside. Iraqi forces “must remain at their posts through the elections.”

An Iraqi-ordered 8 p.m. election curfew is to go into effect across Iraq by midweek.

Otherwise, however, American and Iraqi officials’ election strategies and threat levels differ widely across Iraq.

The American military role in some regions will be more hands-on, including ferrying election workers to the polls in some parts of the country.

The division of election duties in the so-called triangle of death is clear, however: Despite the intensity of the threat, Iraqis – not Americans – are to run the elections and guard the polling places.

Iraqi mobilization for the vote marks the most committed Iraqi effort that American forces here have seen, Colonel Durkin and his officers said.

Iraqi police and national guard units, recreated by American forces here over the past year, have canceled all leaves and days off – putting every well man on duty for the landmark election.

Marines have been funneling supplies to security forces and hospitals in recent days. Iraqi American-trained SWAT teams will deploy – providing a homegrown rapid response to election attacks.

And Iraqis, not Americans, are choosing the polling sites here and providing the poll workers.

“It will be the Iraqis alone who control the elections,” Iskandariyah district police chief Lieutenant Colonel Salman obaid Khadim said from the roof of his sandbagged, barricaded police station. Fears of more attacks are helping make it a stealth election.

Election officials aren’t even telling Americans where Iraqis plan to store ballots locally in the days just ahead of the vote – saying they can protect it themselves.

Iraqis and Americans are waiting until a few days ahead of the vote to make public the location of each polling site, by word of mouth and TV announcements. Security planning for each site has been equally clandestine.