"Three U.S. service members were killed Wednesday in southern Iraq," a military statement said without giving further details about how and where exactly the incident took place.
The names of the deceased are being withheld pending notification of next of kin, the statement said.
The latest announcement brought the number of U.S. soldiers who have been killed in Iraq this month to 15, the highest since June 2009.
Thursday`s deaths take the overall U.S. death toll in Iraq since the March 2003 invasion to 4,469, according to media count based on Pentagon figures.
In mid 2010, U.S. troops in Iraq were reduced to below 47,000 soldiers. Washington said the remaining U.S. troops in Iraq are conducting support and training missions.
The U.S. military forces are to pull out completely from Iraq by the end of 2011 according to the security pact named Status of Forces Agreement, or SOFA, signed late in 2008 between Baghdad and Washington.