WASHINGTON (Reuters) - President Donald Trump will sharply reduce the number of U.S. forces in Afghanistan from 4,500 to 2,500 by mid-January, the Pentagon announced on Tuesday, stopping short of a threatened full withdrawal from America’s longest war after fierce opposition from allies at home and abroad.Trump’s decision to limit himself to a partial withdrawal was first reported by Reuters on Monday but still triggered a rebuke from senior Republicans and Democrats who fear it will undermine security and hurt fragile peace talks with the Taliban. Acting Defense Secretary Christopher Miller, who Trump installed last week after abruptly firing Mark Esper, confirmed the Afghan drawdown and also outlined a modest withdrawal of forces from Iraq to reduce troop levels from 3,000 to 2,500. “By Jan. 15, 2021, our forces, their size in Afghanistan, will be 2,500 troops. Our force size in Iraq will also be 2,500 by that same date,” Miller told reporters. About the same time, the top Senate Republican, Majority Leader Mitch McConnell, cautioned against any major changes in U.S. defense or foreign policy in the next couple of months, including any precipitous troop drawdowns in Afghanistan and Iraq.