"There is nothing being said at all about the troop alignment in Germany or anything that would change the 32,000 troop force that we have in Germany," said a senior administration official, speaking on condition of anonymity.

US troops have been stationed in Germany since World War II, and the country serves as a rear base for US operations in Africa and the Middle East.

The Washington Post recently reported that the Pentagon was evaluating the cost of transferring or withdrawing the troops -- the biggest contingent outside the United States.

The Pentagon had denied any suggestion of a pullout, saying the department regularly reviews its troop positioning and performs cost-benefit analyses -- and that "this is nothing new."

President Donald Trump -- who is heading to Brussels for the July 11-12 NATO summit -- has written to a number of America's partners in the transatlantic alliance, including Germany, to remind them of their commitment to raise defense spending to at least two percent of GDP by 2024.

Following the summit, Trump will head to Britain, and on to Helsinki for a closely-watched face-to-face with his Russian counterpart Vladimir Putin.