US Secretary of Defence Donald Rumsfeld faced a grilling when he visited troops about to face combat in Iraq.
Rumsfeld insisted the troops would prevail
Mr Rumsfeld was at Camp Buehring, Kuwait, to deliver a pep-talk to soldiers about the significance of the task ahead of them.
But he faced tough questions from soldiers anxious about their equipment and how long they will stay.
Pentagon staff said troops regularly quiz senior officers, adding that it was a way of boosting morale.
One soldier said troops were forced to root through rubbish to reinforce their armoured vehicles.
"Why do we soldiers have to dig through local landfills for pieces of scrap metal and compromised ballistic glass to uparmour our vehicles?" Army Spc Thomas Wilson asked.
His question brought cheers from some 2,000 fellow soldiers - mostly Reserve and National Guard troops - assembled in an aircraft hangar for the question-and-answer session that followed Mr Rumsfeld's speech.
Mr Rumsfeld paused, before asking him to repeat the question, AP news agency reported.
Spc Wilson did so, adding, "we do not have proper armoured vehicles to carry with us".
"You go to war with the army you have," Mr Rumsfeld replied, saying vehicle armour manufacturers were being exhorted to crank up production.
Mr Rumsfeld added that vehicle armour might not provide total protection from the perils faced by soldiers in Iraq - such as roadside bombs.
"You can have all the armour in the world on a tank and it can [still] be blown up," Mr Rumsfeld said.
The BBC's Nick Childs at the Pentagon says that while questioning at rallies can often be critical, the comments from the troops this time did seem particularly pointed and some of Mr Rumsfeld's responses rather blunt.
Mr Rumsfeld denied the charge from another soldier that active-duty troops were prioritised above Reserve and National Guard soldiers to receive the best military equipment.
Another soldier asked how long the army would continue to use its powers to extend tours of duty - the so-called stop-loss policy which is currently estimated to be keeping some 7,000 soldiers in Iraq beyond their expected return date.
Mr Rumsfeld said this was simply a fact of life for soldiers at time of war.
"It's basically a sound principle, it's nothing new, it's
been well understood" by soldiers, he said.
"My guess is it will continue to be used as little as possible, but that it will continue to be used."
Rumsfeld faced a sometimes sceptical reception
At one point Mr Rumsfeld's voice broke as he delivered prepared comments to troops before the question-and-answer session.
"You know there are those who see the violence taking place in Iraq... and they say we can't prevail," he said.
"I see that violence and say we must win," he said.
Pentagon officials are likely to be concerned because the questions were being asked by troops about to head for the front line.
Although the Pentagon insists that troop recruitment and morale remain good overall, the longer the conflict in Iraq goes on, the more difficult an issue that's likely to become, our correspondent notes.