The Pentagon on Monday raised its cost estimate of the war against the Islamic State in Iraq and Syria (ISIS) to $8.3 million per day.
The new daily estimate would bring the total cost of the war, between Aug. 8 and Oct. 16, to $580 million, according to Reuters.
The Defense Department last week estimated said the campaign was costing $7.6 million per day, for a total of $424 billion.
The new average reflects increased airstrikes against ISIS, especially in Syria, where the U.S. is trying to protect the border town of Kobani. The average does not include costs incurred in Iraq since mid-June, when President Obama sent advisers to the county to aid the fight against ISIS.
A group that tracks federal spending said Monday the cost of the war will soon cross the $1 billion mark.
"Every hour, taxpayers in United States are paying $312,500 for cost of military action against ISIS," the group, National Priorities Project, said in a statement.