A document believed to be leaked by the U.S. government has revealed that North Korea may have hatched a "hoax" during a recent intercontinental ballistic missile show.

U.S. intelligence analysts say a recent military parade by North Korea "may have exaggerated" the threat Pyongyang's intercontinental ballistic missiles pose to the United States, according to the document.

Reuters reported that more than 50 documents stamped with "secret" and "top secret" seals first appeared on social media in March, apparently revealing details of the military capabilities of some U.S. allies and adversaries.

While the Pentagon did not confirm the authenticity of the leaked documents, it said on Monday that an "unauthorized disclosure of classified material" appeared to have occurred, while the authenticity of the documents could not be independently verified.

The ministry said the images from these documents appeared to be identical in format to those used to give daily briefings to senior commanders, although some appeared to have been altered.

North Korea continues to develop its ballistic missile program and stepped up tests last year (Reuters)

Non-operable systems

A brief one-paragraph note in a classified document seen by Reuters noted that North Korea had displayed an unprecedented number of intercontinental ballistic missile launchers at a February 8 show, which were "likely carrying inoperable systems."

Neither the Pentagon nor North Korea's U.N. mission responded to requests for comment on the authenticity of the Pyongyang section of the document. The document said North Korea's goal was "likely to portray a serious nuclear threat to the United States."

The document added that North Korea "displayed these inoperable systems to show that it has a larger and more capable missile power than it already has, and to mitigate the danger to its real missiles."

North Korea continues to develop its ballistic missile program and tested dozens of advanced missile launches last year despite U.N. Security Council resolutions and U.S.-led sanctions. Pyongyang continued to test missile launches this year.

The leaked images showed about 11 Hwasong-17 missiles, North Korea's largest intercontinental ballistic missile believed to be capable of hitting anywhere in the world with a nuclear warhead.