ERBIL, Iraq-- An ISIS commander blamed for the death of a U.S. Marine was killed Sunday by a drone strike in Iraq.

The ISIS member was said to be behind the rocket attack that killed Staff Sergeant Louis Cardin, and wounded eight other Marines last month.

Also engaged in the fight against ISIS -- with the help of U.S. forces -- are Kurdish soldiers: the peshmerga, and they are running out of money.

For nearly two years, Iraq's Kurdish fighters have led the battle against ISIS.

Known as the peshmerga -- which means "one who faces death" -- these Kurdish soldiers have helped claw back towns, villages and territory from the extremists.

Nearly 1,400 peshmerga have lost their lives in a war they're fighting without enough body armor or helmets to go around -- with very few heavy weapons and against an enemy that uses suicide bombs and booby traps.

"The Kurds are not only fighting for themselves, but for the rest of the world," Masrour Barzani

Masrour Barzani is the head of the security council in Iraqi Kurdistan, a region that's been plunged into economic crisis by the falling price of oil, with consequences for the peshmerga.

Masrour Barzani. CBS News

"They haven't been paid for four months at least," said Barzani.

And they're fighting ISIS on the front line.

"They are. They believe in the cause," said Barzani. "But unfortunately they have families, they have people to take care of, and we don't know for how much longer they can stand in the front lines without being paid."

The Kurds say the war against ISIS has cost them billions of dollars, not only in bullets and fighters' pay, but because they have opened the doors to outsiders.

They taken in 1.8 million people who have fled ISIS, a big burden for such a small place.

"It is, absolutely," said Barzani. "It has increased the population of Kurdistan by almost 30 percent."

And near the front line, just north of Mosul, a city occupied by ISIS, is another potential disaster.

Mosul dam, which was built by Saddam Hussein's regime on weak foundations, has fallen into disrepair, and dangerously so. Engineers warn the dam could break at any time.

What would happen if the dam broke?

"Large part of Mosul will be flooded, in matter of a few hours, and then anything on the way, all the way to Baghdad, it would take a few days to reach Baghdad, but it would be flooded, everything on the way," Barzani said.

The U.S. said it could trigger a 45 foot high flood wave on the river Tigris -- endangering the lives of 1.5 million people in a part of the world already suffering from another man made catastrophe.