It said yesterday that security forces had killed 279 militants and soldiers have recaptured towns north of Baghdad. As troops begin to push back against militants, evidence of brutal violence against soldiers has emerged.
The US condemned a massacre in which ISIL militants appear to have killed scores of soldiers around the conflict-hit city of Tikrit, while the burned bodies of 12 policemen were also found in the town of Ishaqi.
Photos posted online were said to show jihadists summarily executing dozens of captured members of the security forces in Salaheddin province, of which Tikrit is the capital, with tweets attributed to ISIL claiming they had killed 1,700 in all. The photos and the claims could not be verified.
"The claim ... Is horrifying and a true depiction of the bloodlust that these terrorists represent," Psaki said.
Washington has also deployed an aircraft carrier group to the Gulf as US President Barack Obama said he was weighing "all options" on how to support the Iraqi government.But he has ruled out a return to Iraq for US soldiers, who left the country at the end of 2011 after a bloody and costly intervention launched in 2003.
The US and Iran have also raised the possibility of direct engagement over the Iraq crisis, with the Wall Street Journal reporting, citing US officials, that the Obama administration may use nuclear talks starting in Vienna on Monday as a venue.
Iranian President Hassan Rouhani surprised observers by saying days earlier that Iran may "think about" cooperating with Washington, with whom it has not had diplomatic relations for more than three decades. The possibility of US-Iran discussions came as the crisis entered its second week.
After days of unrest elsewhere in the Sunni Arab-majority north and west of Iraq, militants launched an assault on the country's second-biggest city Mosul on June 9, and swiftly moved down to Tikrit, executed dictator Saddam Hussein's hometown.
Iraqi forces performed poorly early on, abandoning vehicles and positions and discarding their uniforms, with militants reaching within less than 100 kilometres of Baghdad.
Baghdad's embattled forces, which have performed better in recent days, will be joined by a flood of volunteers after a call to arms from top Shiite cleric Grand Ayatollah Ali al-Sistani, but a recruitment centre for volunteers came under attack yesterday, leaving six people dead.
