The U.S. was grilled on Monday for its remarks that foreign military forces in Iraq should be there with the approval of Baghdad, regarding the support of the offensive to liberate the Iraqi city of Mosul from Daesh.

"Since when is it the position of the U.S. that any foreign military action in Iraq must have the consent of the Iraqi government?" U.S. State Department spokesman Mark Toner was asked during a press briefing, recalling the U.S.'s 2003 invasion of Iraq, which caused hundreds of thousands of deaths.

"You guys pick and choose that foreign militaries can't operate unless they have this expressed consent of a country's government," a reporter said, who asked the initial question.

In 2003, the U.S. invaded Iraq with more than 100,000 troops to topple Saddam Hussein, due to accusations of the country having weapons of mass destruction. Later, the U.S. and U.K. admitted that there were no weapons of mass destruction in Iraq. Currently, the U.S. is participating in the Iraqi-led Mosul campaign in a train, advisory and assistance capacity.

According to Toner, the Iraqi regime and the set of circumstances were different in 2003 and in the "imminent national security interest of the U.S.," he said, adding, the situations then and now do not have the same standards in place.

Pushed about whether he was aware Iraqi Prime Minister Haider al-Abadi had personally asked Turkey for help after Daesh took control of Mosul in 2014, Toner said he would not "get into past history."

He also said the U.S. has not played any role in the timing of the Mosul operation which began midnight on Sunday.