US officials believe bad news from Iraq gets undue coverage
The US Defence Department said it would expand its public relations work to fight "inaccurate" news stories.
Defence Secretary Donald Rumsfeld has said media manipulation by enemies of the US is the only thing keeping him awake at night.
Domestic support for the war in Iraq has fallen as US mid-term polls near.
The opposition Democrats are trying to win control of Congress from the Republicans.
The newly-established Pentagon unit would use "new media" channels to push its message, a spokesman said.
"We're looking at being quicker to respond to breaking news," the spokesman said.
"Being quicker to respond, frankly, to inaccurate statements."
According to the BBC's Justin Webb in Washington, the Bush administration does not believe the true picture of events in Iraq has been made public.
He says the administration is particularly concerned that insurgents in areas such as Iraq have been able to use the web to disseminate their message and give the impression they are more powerful than the US.
A Pentagon memo seen by the Associated Press news agency said the new unit will "develop messages" for the 24-hour news cycle and aim to "correct the record".
A spokesman said the unit would monitor media such as weblogs and would also employ "surrogates", or top politicians or lobbyists who could be interviewed on TV and radio shows.