WASHINGTON — The Army will eliminate at least 12 combat brigades, relocate thousands of soldiers, and cancel $400 million in construction projects as the first wave of federal budget cuts takes effect.
In a massive restructuring, Army leaders said Tuesday that they will slash the number of active duty combat brigades from 45 to 33, as the Army moves forward with a longtime plan to cut the size of the service by 80,000.
And they warned that more cuts — as many as 100,000 more active duty, National Guard, and Reserve soldiers — could be coming if Congress allows billions of dollars in automatic budget cuts to continue next year.
The sweeping changes would by 2017 eliminate brigades, which number from 3,500 to 5,000 troops, at Army bases in Texas, Kentucky, Georgia, Colorado, North Carolina, New York, Kansas, and Washington state.
The Army will also cut thousands of other jobs across the service, including soldiers in units that support the brigades. Two brigades in Germany have already been scheduled for elimination.
General Ray Odierno, Army chief of staff, said one additional brigade will probably be cut, but no final decisions have been made.
‘‘I know in the local communities it will have its impact,’’ Odierno told reporters Tuesday.
‘‘But we’ve done our best to reach out to them so they understand what the impacts are. We’ve tried to make it as small an impact as possible for as many communities as we could.’’