The United States is planning to drastically cut the size of its military forces in Germany, a move that critics believe will benefit Russia.

US President Donald Trump has said in the past that the US contingent in Germany is no longer needed in the way it was during the Cold War, when Germany was an important buffer between US allies and the Soviet Union.

But in announcing his plan to withdraw 9,500 US personnel, the president said he was making the move for financial reasons, contending Berlin is not on target to meet a commitment made by all NATO members to spend at least 2 percent of gross national product on defense by the year 2024.

"Until they pay, we're removing our soldiers, a number of our soldiers," the Associated Press quoted him as saying.

He added that "we're putting the number down to 25,000 soldiers".There are currently 34,500 US troops in Germany.

Trump added that Berlin has been treating the US poorly on trade while benefitting from the spending of US military personnel.

"We're protecting Germany and they're delinquent," he said. "That doesn't make sense."

He also warned other NATO members not to rely too heavily on the US.

The BBC's defense correspondent, Jonathan Marcus, said: "Strategic experts see this as a step that can only benefit Russia and weaken NATO as a whole."

He added that many US allies "already see the Trump administration as an unpredictable and increasingly unreliable partner "and that this latest move will not help that perception.

While Germany is no longer the Cold War lynchpin it was, it has continued to be important to the US military machine and hosts several US facilities and acts as a conduit for troops heading for the Middle East.

Trump's critics said the president seemed to have overlooked the fact that US troops were largely in Germany because it was in Washington's best interests, a point that was reiterated by Germany's ambassador to the US, Emily Haber.

Several US politicians, including many from Trump's own Republican party, have criticized the move.

William McClellan Thornberry, a member of the House of Representatives and its Armed Services Committee, wrote an open letter in which he said: "The threats posed by Russia have not lessened, and we believe that signs of a weakened US commitment to NATO will encourage further Russian aggression and opportunism."

And fellow Republican, Congresswoman Liz Cheney, said: "Withdrawing our forces and abandoning our allies would have grave consequences, emboldening our adversaries and making war more, not less, likely."

Daily Telegraph newspaper noted that Trump told reporters the US had 52,000 soldiers in Germany while the Pentagon said there are around 34,500.