the breaking news out of Iraq, where today, the U.S. Launched another wave of air strikes. This time, centered around the country's most strategic dam, which has fallen into the hands of the terror... See More
the breaking news out of Iraq, where today, the U.S. Launched another wave of air strikes. This time, centered around the country's most strategic dam, which has fallen into the hands of the terror group Isis, a group that now appears to be more powerful and dangerous than ever. ABC's chief foreign correspondent terry Moran is on the ground tonight in the northern Iraq. Reporter: Reporter: The mosul dam, seized by Isis fighters nine days ago and today, usair strikes pounding those Isis positions, supporting Iraqi troops desperate to retake the dam from a few hundred Isis defenders. That dam's a potential weapon of mass destruction, if Isis blows it up, it could send a wall of watt earl 60 feet high through the city of mosul and flood Baghdad, 250 miles away. But the Isis tide rolls on. Reports of another massacre, at least 80 men rounded up and killed, more than 100 women abducted. We showed this man from the same village pictures of the atrocity. He fled last week. Now he sees his neighbors are dead. In the past few months, Isis has seized control of nearly one-third of Iraq in their brutal and fanatical campaign. The cities of mosul, tal afar and fallujah, much of the border between Iraq and Syria and now, threatening the oil-rich kurdish stronghold of erbil. The kurdish defenses here are pretty primitive, as you can see. Just these dirt berms and a lightly manned outpost in the distance. Beyond that, Isis. U.s. Intelligence officials say the Isis Numbers are growing, swelling, and they've got the momentum here and across much of Iraq. Protecting erbil and its oil now a major U.S. Goal. That's why president Obama ordered usair strikes against Isis forces near the city this week. A new U.S. Intelligence assessment says that Isis poses a direct threat to the American homeland. So, what happens here in northern Iraq in the battle for erbil matters a lot back home. Dan? Scary prospect. Terry, thank you. So, let's bring in ABC's chief white house correspondent Jon Karl. Jon, when the president authorized air strikes, he said they would be used only to, a, protect Americans, or B, prevent a humanitarian disaster. So, are these strikes near the dam consistent with that or is this mission creep here? Reporter: It sure looks like mission creep, Dan. As you point out, the president was very specific, saying just those two purposes. Protecting Americans in Iraq and breaking the seize of Mt. Sinjar. Now you have air strikes aimed at helping Iraqi and kurdish forces retake this dam. Now, the white house uncysts it's actually not mission creep, because that dam were to be broken, it would actually send flood waters all the way to Baghdad and could threaten the U.S. Embassy in Baghdad. And they say that the president has been insistent, publicly and privately, that there will be no mission creep, but there's no question that we now see air strikes in a new phase in this effort in Iraq, Dan. And the president has refused to put a timetable on those air strikes. Jon Karl, thank you.
This transcript has been automatically generated and may not be 100% accurate.