The intelligence specialist is also suspected of possible involvement in the massive leak of more than 92,000 classified military files releated to the war in Afghanistan.
'Life in prison'
Al Jazeera's Rosiland Jordan, reporting from Washington, said that Manning could potentially face the death penalty if he is convicted with leaking the Afghan information in addition to the Iraq video.
"Certainly he [could be] looking at life in a military prison in the US" if convicted, she said.
The Pentagon and the Federal Bureau of Investigation (FBI) have launched an investigation into the leak of Afghanistan documents while US leaders and Hamid Karzai, the Afghan presiden, have condemned the leak.
In a statement, the defence department said Manning was transfered to the US "due to a potentially lengthy pre-trail confinement because of the complexity of the charges and an ongoing investigation."
Our correspondent said that the US military wants to use Manning to send a message to future whistleblowers.
"If you violate the trust of security clearance, you will be prosecuted," she said.
Julian Assange, the founder of WikiLeaks, has called Manning a "political prisoner" and alleged that the US kept him in detention in Kuwait to render him "incommunicado".