The U.S. government has announced intentions to withdraw nearly 12,000 troops from Germany. 

CNN reports that the decision has attracted bipartisan congressional opposition and angered U.S. allies who see the move as a blow to NATO.

Defense officials say pulling thousands of troops from Germany will take years to execute and potentially cost billions of dollars to facilitate.

Others are concerned that the move will weaken the U.S. military's position vis a vis Russia.

Approximately 11,900 US troops, a mix of Army and Air Force units, will be removed from Germany to meet President Donald Trump's mandated cap of 25,000 US forces in Germany, according to a senior U.S. defense official, a number higher than the figure of 9,500 that was used when the reduction was first announced.

The formal announcement was made Wednesday during a briefing at the Pentagon by Defense Secretary Mark Esper.

"The current EUCOM plan will reposition approximately 11,900 military personnel from Germany, from roughly 36,000 down to 24,000, in a manner that will strengthen NATO, enhance the deterrence of Russia, and meet the other principles I set forth," he told reporters, referring to U.S. European Command which oversees US military forces on the continent.

Officials said the discrepancy was due to the fact that following a review it was found that there were slightly more US troops permanently assigned to Germany, about 36,000, than originally planned for.

Of the troops leaving Germany some 5,400 will be "staying in Europe," the official said. The remaining 6,400 forces and their families will be returned to American soil before eventually being redeployed to Europe.

Defense officials said this will cost billions of dollars as new military construction will likely be required both in Europe and the US to house the additional troops.

Key US command centers will also be repositioned as part of the move, Esper and top military leaders confirmed Wednesday.

Gen. Tod Wolters, the commander of US European Command and NATO's Supreme Allied Commander Europe, said the U.S. would be moving EUCOM headquarters from Germany to Belgium as part of an effort to co-locate the command with the NATO military command headquarters that is based there, and that Africa Command headquarters may be moving to a location to be determined as well.

"We also intend to reposition three brigade-size headquarters, an air defense artillery battalion, and an engineering battalion to Belgium from Germany, and two smaller support and contracting organizations to Italy," Wolters told reporters at the Pentagon.

Wolters further specified that a F-16 fighter squadron would be moved from Germany to Italy, and that they anticipated moving two battalions from Germany to Italy as well.

The defense official confirmed that the repositioning will take "months to plan and years to execute," a timeline first revealed earlier this month by the Chairman of the Senate Armed Services Committee Sen. Jim Inhofe who had been briefed on the plan.

The timeline suggests that the plan could be reversed should Trump lose the election in November.

Defense officials say that the German Defense Minister, Annegret Kramp-Karrenbauer, and Secretary General of NATO, Jens Stoltenberg, had been briefed on the planned drawdown as well as key members of Congress.

Defense officials said that Secretary of Defense Mark Esper indicated the repositioning was implemented to enhance deterrence against Russia, strengthen NATO, and support families of US service members.

However President Trump, who directed the move, said he did so because of Berlin's failure to meet the NATO target of spending 2% of GDP on defense, spending only about 1.38%.

"One of the only countries that hasn't agreed to pay what they're supposed to pay (on NATO) is Germany. So, I said until they pay, we're removing our soldiers, a number of our soldiers, by about half. Then when we get down to about 25,000, we'll see where we're going," Mr. Trump said last month.

Defense officials however said Wednesday that the decision as to where to house the U.S. troops leaving Germany was not influenced by whether the new host country was meeting the two percent target.

In fact Belgium and Italy, the two countries that will be receiving American troops from Germany, spend an even a smaller percentage on defense than Berlin does.

Italy spends about 1.22% of its GDP on defense spending while Belgium spends about 0.93% of its GDP on defense, ranking near the bottom among NATO members.

While Germany's national leadership has been largely silent on the troop cuts, local leaders representing the states where U.S. troops are housed recently wrote to members of the US Congress asking them to help reverse the decision.

''We plead for this profound partnership to continue and for U.S. forces to remain at their locations in Europe and Germany," the leaders of the German states of Baden-Wuerttemberg, Rhineland-Palatinate, Hesse and Bavaria wrote.

"We therefore ask you to support us as we strive not to sever the bond of friendship but to strengthen it, and to secure the U.S. presence in Germany and Europe in the future," the letter added.