It is a tricky balance for the troops of Charlie Company, 82nd Airborne Division.
Mr Nice Guy, or Mr Nasty?
By night, these highly trained American soldiers carry out dangerous raids to round up suspected insurgents, men suspected of anti-coalition activities including ambushes and roadside bomb attacks.
The raids usually involve kicking down doors, and sometimes exchanges of heavy gunfire, too.
But by day Charlie Company play the nice guys rather the tough guys.
I followed them to two villages near al-Yousifiyah south-west of Baghdad, where they were trying to win the hearts and minds of the population.
The hardened troops of Charlie Company arrived laden with gifts. There were blankets, coats and heaters for the cold and elderly.
There were pencils, crayons and exercise books for the children, though they seemed rather more interested in the shiny silver footballs also being handed out in the great American giveaway.
It was rather like a road show going from village to village: these US troops suddenly transformed into an army of Father Christmases, doling out presents to almost anyone who wanted one.
I watched them distributing free money too.
Charlie Company's commanders were carrying thousands of dollars to give to good citizens who promised to fix things in their village.
An official at the local water treatment works got $900 to help him with his generator, while someone at the school down the road was pleasantly surprised to have 10 crisp $100 bills thrust into his hands.
It was to put a new door and windows on the school, but who was to say the man would not just pocket all the cash?
Well, the Americans took his picture with a digital camera and warned him they would come back and track him down if he did not do the work he had promised to.
Naive? No, say the Americans: simply a fast and direct method of getting things done in post-war Iraq.
But Charlie Company came armed not only with gifts and dollars - on their road show they also had a US army doctor, travelling in a state-of-the-art mobile medical clinic.
He was offering on-the-spot health care to any villager who wanted it.
Free health care to any villlager who wants it
The aim of all of this is to win the hearts and minds of suspicious Iraqis, to persuade them the Americans are here as friends and helpers, not just as an army of occupation.
Charlie Company know their nocturnal raids inevitably antagonise some Iraqis: smashing into peoples' homes in the middle of the night is never likely to win friends in tightly knit communities.
But they hope their largesse more than makes up for it.
So what do the troops themselves prefer, kicking down doors or giving out goodies?
"I like doing raids myself, because it gives us a chance to go after the bad guys," admits Sergeant Mark Ward, with admirable honesty.
"As a soldier you're supposed to be able to make the transition between respect and violence," adds Sergeant Angelo Bumagat.
"You've got to be good at both to be good at this job. You've got to know how to hand out the crayons and kick the doors down."