The U.S. has been training the Iraqi army for a decade and they have been performing abysmally in most areas.

"The Iraqi forces, unfortunately, as a result of actions taken by the previous government, were in many aspects hollowed out," Deputy U.S. National Security Adviser Tony Blinken told CBS News correspondent Elizabeth Palmer in Iraq. "They were deprofessionalized. Competent commanders were moved out. Incompetent ones were moved in based on loyalty to the government."

The Islamic militant group ISIS is making inroads in Iraq despite international airstrikes there and in Syria.

While ISIS militants have lost ground in several strategic areas, Blinken said "it's a mixed picture" as they gain ground in key strategic territory leading to Baghdad.

Blinken said that he would not rule out the possibility of more U.S. advisers on the ground.

"But what I will rule out, very clearly, is something the president's been very clear about, which is you will not have American combat forces fighting on the ground as they were in the past decade," Blinken said.

Asked if foreign boots would be seen on the ground, Blinken responded: "One of the things we've learned over the past decade is that in these very complex and highly charged situations, when you introduce foreign elements it makes it even more complicated."