The United States hailed the end of the Islamic State group's "vile occupation" of Iraq Saturday after the Baghdad government declared victory in a three-year war, but warned that jihadists still posed a threat.

"The Iraqi announcement signals the last remnants of ISIS's self-proclaimed 'caliphate' in Iraq have been erased and the people living in those areas have been freed from ISIS's brutal control," State Department spokeswoman Heather Nauert said.

"The United States joins the Government of Iraq in stressing that Iraq's liberation does not mean the fight against terrorism, and even against ISIS, in Iraq is over," Nauert added in a statement.