On Saturday, Oct. 4, day 58 of the American campaign against the self-proclaimed Islamic State, U.S. aircraft carried out nine strikes inside Iraq and Syria, destroying two tanks, three Humvees, one bulldozer, and an unidentified vehicle. The strikes also hit several teams of IS fighters and destroyed six of their firing positions.

At first glance, that might seem like a lot of damage. Leaving aside the significance of killing IS militants and only looking at equipment, the tanks were worth an estimated $4.5 to $6.5 million apiece and each Humvee cost $150,000 to $250,000, bringing the total value of the equipment destroyed to somewhere between $9.5 and $13.8 million.

But that's less impressive when one considers that each U.S. "strike" against the self-proclaimed Islamic State can involve several aircraft and munitions and cost up to $500,000, according to Todd Harrison, an expert with the Center for Strategic and Budgetary Assessments, a Washington-based defense think tank.

Harrison said the cheapest possible strike could cost roughly $50,000 - assuming a single plane dropping one of the cheaper types of bombs. But the majority of airstrikes cost much more, involving F-15s, F-16s, F-22s, and other aircraft that cost $9,000 to upwards of $20,000 per hour to operate and explosives that cost tens to hundreds of thousands of dollars. Harrison noted that each strike's price "depends on the distance to the target site, how long it may need to loiter, what type of aircraft is used, and whether it needs aerial refueling (and how many times)."

But using his $500,000 upper estimate, Saturday's strike missions alone cost as much as $4.5 million. And those figures don't even include the intelligence, surveillance, and reconnaissance flights necessary to scope out targets ahead of strikes, which have helped make even the low-level campaign against the IS hugely expensive. The Pentagon revealed on Monday that it has spent as much as $1.1 billion on military operations against the Islamic State since June.

Even more disheartening, most, if not all, of the equipment being destroyed originally came from the United States - which is why we're able to estimate its worth.

Even more disheartening, most, if not all, of the equipment being destroyed originally came from the United States - which is why we're able to estimate its worth. It was given to the Iraqi Army ahead of the U.S. military's withdrawal in 2011 and captured by the IS when it advanced into Iraq earlier this year. That means Washington is now spending hundreds of millions of dollars from the U.S. Treasury to destroy Humvees, tanks, and other weapons that American taxpayers purchased. The situation has led some observers to joke that the Pentagon should christen the mission "Operation Hey, That's My Humvee."

Saturday's strikes are indicative of a key complexity of the U.S.-led campaign in Iraq and Syria: In throwing its hugely expensive 21st-century weaponry at a band of insurgents, the Pentagon is using planes that can cost nearly $200 million apiece against pickup trucks costing virtually pennies in comparison.

That's not a new problem for the United States. In the aftermath of the Sept. 11 attacks, President George W. Bush famously told four senators that he wasn't "going to fire a $2 million missile at a $10 empty tent and hit a camel in the butt."

Just one Tomahawk cruise missile costs more than $1 million. The United States launched at least 47 last month

Just one Tomahawk cruise missile costs more than $1 million. The United States launched at least 47 last month, though many of them reportedly targeted the mysterious Khorasan Group, and not the IS.

Clearly, even though U.S. engagement so far has taken the form of airstrikes rather than "boots on the ground," the costs haven't been low. What's not clear from Pentagon reports is just how those costs measure up against the aggregate value of the fighters, equipment, and infrastructure the Sunni militant group has lost in the strikes.

As to the number of militants killed, the Pentagon has reported only that airstrikes have hit three large units, several small units, and an unspecified number of other fighters.

To be fair to the Pentagon, though, the cost of the equipment destroyed is a hard number to tally. It's difficult to know exactly when particular pieces of the U.S. hardware now in the hands of ISIS, as the group is also called, were sent to Iraq, and what that value is now after accounting for depreciation. That makes the above price tags for equipment, which use today's "sticker price" for tanks and Humvees, generous estimates of the vehicles' actual value when destroyed.

Even so, 62 days after air campaign began, and $1.1 billion dollars later, U.S.-led strikes have destroyed arms and vehicles totaling just $123 million to $173 million, by Foreign Policy's estimate. Granted, that estimate doesn't account for the harder-to-calculate value of other damaged or destroyed ISIS equipment and infrastructure, including portions of valuable oil refineries under IS control. Since expanding airstrikes from Iraq to Syria, the United States and its Arab coalition partners have carried out 16 strikes on ISIS-held oil refineries.

That could represent a significant dent in the IS's revenues. These Syrian refineries reportedly earn the group $2 million per day. Refineries in Iraq, which so far haven't been hit by U.S.-led airstrikes, make the group about $1 million per day. On Sept. 25, the Pentagon said it had crippled most of the Syrian refineries. But, as Foreign Policy reported on Tuesday, just how crippled they are remains unclear.

Besides, most airstrikes haven't targeted refineries. In addition to striking equipment originally from the United States, they've hit things like IS improvised explosive device (IED) emplacements, fighting positions, checkpoints, training camps and garrisons, weapons storage and manufacturing facilities, ISIS-held airfields, and various other buildings. The value of many of these targets is relatively insignificant. On Sept. 16, five U.S. airstrikes managed only to destroy one truck, one anti-aircraft artillery piece, two small boats, and one fighting position. With estimates for the cost of five airstrikes going as high as $2.5 million, that means the United States used an awfully expensive hammer to hit a couple of relatively cheap nails.

Another recent Central Command press release, using a different acronym the militant group is known by, touted the destruction of "an ISIL guard shack" among its victories. The weapon that destroyed the guard shack would have cost tens of thousands of dollars, and would have been dropped by an aircraft that, likewise, cost tens of thousands to fly. The shack may not have been very expensive to build, but it certainly was pricey to destroy.

(c) 2014, Foreign Policy