The US is set to withdraw almost 12,000 troops from Germany in what it described as a reconsideration of its strategy in Europe.
About 6,400 troops will be sent home, with some remaining in Nato countries such as Italy and Belgium.
President Donald Trump said the move was a response to Germany’s failure to meet Nato’s terms of defense spending.
But it has drawn widespread opposition in Congress from those who believe it will oppose Russia.
Top German officials have also expressed concern.
“We no longer want to be needy,” Mr. Trump told reporters at the White House on Wednesday shortly after the announcement was made. “It’s depressing because they don’t pay their bills; it’s very easy.”
Mr Trump has long lamented that Nato members of Europe should spend more money on self-defense. He also said that Nato members should no longer rely too much on the US to meet the cost of maintaining the coalition.
The dispute between the coalition focuses on an agreed-upon target by all members of the organization that defense spending should reach 2% of GDP (gross domestic product, total value of goods produced and services provided in the country) by 2024. Germany, and many other countries, still have to meet this guideline.
Defense Secretary Mark Esper took a different tone when announcing the decision, stressing that it was part of a broader reorganization of US troops in the region.
He said it was “a great change for the better and better” that would make “important goals to increase the victory of Russia and Nato Russia”.
The project will cost the US government billions of dollars and will reduce military presence in Germany by more than 25 percent.
The war veterans will be deported to Italy while other troops will not be relocated to Poland, Mr Esper said.
The decision was criticized by German officials, the chairman of the country’s foreign affairs committee, who said it would “weaken the NATO alliance”.
And the head of the Bavarian state, Markus Soeder, said he regretted the decision. “This puts a strain on German and American relations,” he told reporters.
There was also bipartisan criticism in Washington. “This is self-destructive … in line with American interests,” said Democratic Senator Jack Reed.
Republican Senator Mt Romney described the decision to withdraw troops from Germany as “a serious mistake” and “slapping friends and acquaintances”.
The plan was first announced by Mr Trump last month, when he accused Berlin of “colluding” with its Nato paycheck. He also accused Germany of treating the US “too badly commercially”.
He also said that Germany had benefited from getting troops there because the soldiers were spending their money on the country.
The presence of American troops in Germany is a legacy that existed after the outbreak of World War II in this country. Germany currently holds the largest number of US troops in Europe, followed by Italy, the UK and Spain.
Some U.S. personnel based in Europe support non-Nato missions and the numbers of U.S. troops are changing as troops move in and out of Europe.