Proving that Iraq’s army faces a long road ahead before it can stand on its own, American troops joined the Iraqis in battle Sunday in fighting off a bruising Sunni insurgency. The U.S., whose primary task is now to advise and train Iraq’s army, joined in firing on insurgents about 50 miles from Baghdad, a standoff that resulted in the deaths of three Iraqis but no Americans. U.S. troops—among the 50,000 still stationed in Iraq after the September 1 withdrawal—provided helicopters, snipers, and aid in defusing bombs after Iraqi troops could not locate the source of the insurgent fire. Since the end of the U.S. combat mission, the Iraqi army’s readiness to assume control over defending the country has been a major source of concern for American military leaders. The military has not confirmed its role in today’s battle.