The United States plans to significantly reduce the aircraft and warships that it makes available for NATO operations in Europe, according to two senior European officials, accelerating America’s effort to scale down the protection it has offered to European allies for eight decades.

The decision would limit NATO’s ability to launch long-range strikes and conduct surveillance. It was communicated to allies in early June in a written document, parts of which were reviewed by The New York Times. The European officials, who were briefed on the decision, spoke on the condition of anonymity to speak more freely about sensitive military plans.