Iraqi forces have assumed formal control of the capital, Baghdad, and other cities, six years after US-led coalition forces invaded Iraq.
US troops began withdrawing from the country's major cities and towns as the midnight deadline passed on Tuesday for troops to hand over security to Iraqi forces.
"The withdrawal of American troops is completed now from all cities, after everything they sacrificed for the sake of security," Sadiq Al-Rikabi, a senior adviser to Nuri al-Maliki, the Iraqi prime minister, said.
The top US commander in Mosul has warned Iraqi army generals that the time has not yet come for his forces to pull out.
"The most dangerous thing that can happen to you and me is that the insurgents separate us, to put a wedge between us," Colonel Gary Volesky said.
The Iraqi army and government have asked that Volesky's troops remain in Mosul past the scheduled withdrawal date.