CNN  — 

Documents containing highly sensitive intelligence about Iran and China were among those recovered by the FBI from former President Donald Trump’s Mar-a-Lago estate, The Washington Post reported on Friday.

Disclosure of the documents’ contents could expose US intelligence-gathering methods, people familiar with the matter told the Post. At least one of the documents describes Iran’s missile program and others described highly sensitive intelligence involving China.

The Post’s sources characterized the documents as among the most sensitive recovered by the FBI since it began its investigation of the former President and his aides into the potential mishandling of classified information.

A Trump spokesman did not immediately respond to requests for comment to the Post on Friday morning.

The people familiar with the matter who spoke to the Post said many of the more sensitive documents taken to the resort are analysis papers that do not contain sources’ names, though they can still provide insight to foreign adversaries. Some of the documents are only available to the highest-level officials in the US government, such as the President or Cabinet members.

CNN has reported that since the FBI search in August, the US intelligence community has restarted work on both the classification review and the so-called damage assessment related to Trump’s storage of classified materials at Mar-a-Lago.

The damage assessment is a long-term analytic product that will study what the risk would be to US national security if the material stored at Mar-a-Lago were to be exposed. The classification review is designed to review each document to establish that its classification markings are current.

On Thursday, CNN reported that Trump’s legal team is weighing whether to allow federal agents to return to the former President’s Florida residence, and potentially conduct a supervised search, to satisfy the Justice Department’s demands that all sensitive government documents are returned, sources tell CNN.

In private discussions with Trump’s team as well as court filings, the Justice Department has made clear that it believes Trump failed to comply with a May subpoena ordering the return of all documents marked as classified and that more government records remain missing.

Some in Trump’s inner circle aren’t convinced there are any remaining government documents, after the FBI seized nearly 22,000 pages when they executed a search warrant at Mar-a-Lago in August.