BRUSSELS—The Obama administration has scaled down plans begun under President George W. Bush to bring home two army brigades from Europe, saying it intends only to remove one brigade, and will delay its withdrawal until 2015, a senior U.S. official said Friday.

The decision will leave some 80,000 U.S. troops in Europe from 2015, the year after U.S. troops are scheduled to end their combat mission in Afghanistan. That is the highest number of U.S. troops on European soil since the start of the Iraq war in 2003, said the senior official. That's because many of those serving in Iraq and Afghanistan have been stationed in Europe.

In 2004, the U.S. announced plans to reduce forces in Europe, to around 60,000 from 100,000, while Donald Rumsfeld was Defense Secretary. The plans were put on hold in 2007 by the Bush administration, soon after Mr. Rumsfeld was succeeded by current secretary Robert Gates. That reflected disquiet among senior officers that basing too many troops in the U.S. would keep them too far away from potential trouble spots in Africa and the Middle East.

The plan was put under formal review when the Obama administration came into office, and resulted in Friday's decision.

The brigade to be withdrawn will be a heavy army unit, yet to be determined, based in Germany. It will keep three brigades in Europe: one heavy brigade, one of Stryker armored vehicles, and an airborne brigade. The U.S. will also move into Europe more CV-22 Osprey aircraft to provide airlift for special-operations forces, more Aegis-class ships to provide missile defense capabilities and set up an air training unit in Poland, the U.S. official said.