WASHINGTON — Gen. Ray Odierno, the Army chief of staff, said Tuesday that the Army would institute the largest organizational change since World War II by eliminating combat forces from 10 bases across the United States, part of a planned reduction of 80,000 active-duty troops over the next five years.

The announcement supports the Army’s effort to downsize the active-duty force to 490,000 as the military winds down from the wars in Iraq and Afghanistan. The cuts were a result of the 2011 Budget Control Act that required $487 billion in military spending cuts over a decade. This is the fourth round of budget cuts for the military since President Obama took office.

Under the plan, the Army will cut its brigade combat teams to 33 from 45 by 2017 at bases in Colorado, Georgia, Kansas, Kentucky, New York, North Carolina, Texas and Washington State. A brigade is roughly 3,500 to 5,000 people. Two additional brigades in Germany, at Baumholder and Grafenwöhr, have already been scheduled for elimination this year.

General Odierno said the cutbacks are only a precursor to further action. “There is going to be another reduction,” he said at a Pentagon news conference. “There is no away around it.”