BAGHDAD - Since President Barack Obama declared an end to combat operations in Iraq, U.S. troops have waged a gun battle with a suicide squad in Baghdad, dropped bombs on armed militants in Baquba and assisted Iraqi soldiers in a raid in Falluja.

Obama's announcement on August 31 has not meant the end of fighting for some of the 50,000 U.S. military personnel remaining in Iraq 7-1/2 years after the invasion that removed Saddam Hussein.

"Our rules of engagement have not changed. Iraq does remain from time to time a dangerous place, so when our soldiers are attacked they will return fire," said Brigadier General Jeffrey Buchanan, a U.S. military spokesman.

The American role in Iraq's battle to quell a tenacious Islamist insurgency has been waning since security in cities and towns was handed over to Iraqi police and soldiers in June 2009.

Officially, U.S. forces remain in Iraq to "advise, train and assist."

When they answered a call for help two weeks ago from Iraqi soldiers overwhelmed in a gunfight with militants hiding in a palm grove near Baquba in Diyala province, U.S. troops brought in attack helicopters and F-16 jet fighters.

More private military contractors than uniformed service members were killed while serving in Iraq and Afghanistan between January and June of this year, marking the first time that corporations have lost more personnel on America’s battlefields than the United States military, according to ProPublica, the nonprofit investigative reporting group. More than 250 civilians working under American contractors were killed in Iraq and Afghanistan during the first six months of 2010, while 235 soldiers died in that same period, according to the latest report in ProPublica’s Disposable Army series.

The numbers, while disheartening, are not surprising. Private contractors have provided more support operations for America’s military campaigns in Iraq and Afghanistan than for any other armed conflicts in United States history. With the Aug. 31 drawdown of American combat troops in Iraq and the reliance on contractors for covert operations in Afghanistan and Pakistan, it seems likely that the contractor death toll will continue to climb.

There were 207,600 private contractors employed by the Department of Defense, 19 percent more than the 175,000 uniformed personnel members employed by the department, according to a July report by the Congressional Research Service. In Iraq and Afghanistan, contractors make up 54 percent of the Defense Department’s workforce, according to the report.

As of June, contractor deaths represented over 25 percent of all United States fatalities since the beginning of the Iraq and Afghanistan campaigns, according to a report by Steven L. Schooner and Collin D. Swan at the George Washington University Law School.

Arlington National Cemetery officials said they are making progress in rectifying the problems with more than 200 gravesites identified in an Army Inspector General's report by verifying the paperwork, using ground-penetrating radar, and, in a few cases, digging up graves with a backhoe

But even though it has been four months since the report was released, many of the record-keeping issues remain unresolved, the full scope of the problems at the nation's premier military cemetery is not yet known, and the cemetery's leadership cannot say how long it will take to fix the situation.

In a statement, Kathryn Condon, the newly appointed executive director of the Army National Cemeteries Program, said cemetery officials "are working diligently each and every day to correct the mistakes made in the past and restore the dignity and honor our nation's heroes deserve."

The IG report, released in June, detailed a chaotic management system at the cemetery, poor record-keeping and discrepancies between burial maps and what was actually in place.

Investigators found that 117 gravesites without headstones were marked as occupied on cemetery maps; 94 others, with corresponding headstones, were marked as empty on the maps.