Cost of fighting ISIS already approaching $1 billion

Just what is the dollar amount the U.S. government has spend fighting the Islamic State militant group, also known as ISIL or ISIS?

Well, the U.S. has already spent nearly $1 billion fighting the terrorist group.

And experts say the cost would go up drastically if ground troops were added.

The Center for Strategic and Budgetary Assessment released a study of the estimated costs.

That study found that U.S. military air operations against ISIS would cost about four billion dollars a year.

Adding 25,000 ground troops would increase the cost to $1.8 billion dollars a month, though President Obama said he has no plans for U.S. ground troops.