He wrote on the Truth Social platform that he made the decision based on the fact that Poland last year elected Trump favorite, Karol Nawrocki, as its new president.
As recently as last week, it was reported that the US had halted the deployment of 4,000 soldiers en route to Poland as part of a broader reorganization of US forces in Europe.
Trump did not specify what his announcement means for the total American presence in Poland and in Europe as a whole.
In early May, the Pentagon announced that the US would reduce its presence in Germany by 5,000 soldiers, and Trump later said that there could be significantly more than that.
The decision came after German Chancellor Friedrich Merz - to Trump's great anger - criticized the US war on Iran.
