The decision was not a "withdrawal," Romania's Defence Minister Ionut Mosteanu told journalists shortly after the statement was released.

It was the "cessation of the rotation of a brigade that had elements in several NATO countries, including Bulgaria, Romania, Slovakia and Hungary", he said.

The ministry statement said that 1,000 US soldiers would remain deployed in Romania.

They will help "to deter any threat" and represent "a guarantee of the United States' commitment to regional security", said Mosteanu.

A NATO official told AFP that the body had been informed by the administration of US President Donald Trump in advance and also played down its significance.

"Even with this adjustment, the US force posture in Europe remains larger than it has been for many years, with many more US forces on the continent than before 2022," the official said, adding Washington's commitment to the alliance remained "clear".

Mosteanu said strategic capabilities were "unchanged", specifying that "the missile-defence system at Deveselu remains fully operational.

"The Campia Turzii air base continues to be a key point for air operations and allied cooperation, the Mihail Kogalniceanu base continues to be developed, and the American flag will remain present at all three sites," he continued.

"An air-combat group will remain at the Kogzlniceanu airbase, as was the case before the outbreak of the conflict in Ukraine," he added.

His ministry also said "the decision was expected" and was "the result of the new priorities of the (US) administration, announced in February".