It’s become routine to read in the news about private military contractors in Iraq and Afghanistan. They provide everything from tactical combat operations to logistical support and technical assistance. These modern corporate mercenaries play a vital role in Iraq, but their extensive use there and in other hot spots around the globe is raising a host of problems. They’ve been accused, for example, of profiteering and taking part in the abuse of Iraqi prisoners.

There are more than 60 private firms, employing more than 20,000 people, carrying out military functions in Iraq. Private contractors have suffered more casualties—an estimated 175 killed and 900 wounded—than any single U.S. Army division, and more than all the United States’ coalition partners combined.

Contractors handled logistics and support during the Iraq War’s buildup; they maintained and loaded B-2 stealth bomb­ers and other sophisticated weapons systems during the 2003 invasion; and they’ve been even more widely used in the occupation and counterinsurgency effort. Halliburton’s Kellogg, Brown & Root division, the largest military firm in Iraq, provides troop supplies and equipment maintenance under a Pentagon contract estimated at $13 billion. Other firms are being used to help train Iraqi forces, protect important installations and individuals, and escort convoys.

But unlike military forces, private firms can abandon operations that become too dangerous or otherwise too costly, and their employees are free to walk off the job. More than once, the U.S. military has been left in the lurch.

Being “not quite soldiers” and “not quite civilians,” the private firms’ employees “tend to fall through the cracks of current legal codes.” The consequences for them can be dire, as three American employees of California Microwave Systems found when their plane crashed in rebel-held territory in Colombia in 2003. Unprotected by the Geneva Conventions, they’ve been held prisoner for the past two years, and both their corporate bosses and the U.S. government “seem to have washed their hands of the matter.”

Their murky legal status has also allowed private military contractors to escape prosecution for crimes in Iraq. The U.S. Army found that contractors were involved in more than a third of the incidents in the Abu Ghraib prisoner abuse case, but not one of the six employees identified as participants has been indicted.

The private military firms are, in effect, competing with the government, observes Singer, a senior fellow at the Brookings Institution and the author of Corporate Warriors (2003). “Not only do they draw their employees from the military, they do so to play military roles, thus shrinking the military’s purview. [The firms] use public funds to offer soldiers higher pay, and then charge the government at an even higher rate.” And some were not even competent.

Yet military contractors of this type are here to stay. They’ve proliferated since the end of the Cold War, and many governments make use of their services. Singer argues that outsourcing can be beneficial where it will save money or improve quality, but the process needs to be made more open and accountable. More of the contracts should be awarded on a competitive basis (only 60 percent of the Pentagon’s currently are). And military functions critical to the success or failure of an operation should be kept within the military itself.