The Department of Homeland Security has directed its agencies to review and assess who has access to classified information, according to an internal memo obtained by CNN -- a move that comes on the heels of a leak of highly classified Pentagon documents discovered earlier this year.

The memo doesn't cite the leaked Pentagon documents but is in response to it and intended to avoid distributing sensitive information to personnel who don't need it to perform their duties, according to a source familiar.

The memo, dated May 15, calls on agencies to "review and validate" the number of personnel who require access to Classified National Security Information, "with particular attention given to those having access to Sensitive Compartmented information," by the end of June. That includes, for example, employees, contractors, task force offices, and state, local, tribal, and private sector partners.

The objective of the review, the memo says, is not to "arbitrarily reduce" the number of security clearances and/or access but to ensure that current clearance and access levels are still required for official duties and missions. The effort comes at the direction of Secretary Alejandro Mayorkas, the memo says.

Asked by CNN what measures DHS was taking after the Pentagon leaks, Mayorkas said the department issued a reminder to employees and that he had directed a review.

"We issued a reminder of the obligations that guide our employees with respect to the handling of classified information," Mayorkas said during a reporter roundtable in April, adding that he had directed a review of "architecture that we have for providing individuals with clearances."

CNN reached out to DHS for comment on the Monday memo.

Last month, the Biden administration scrambled to deal with the fallout from the revelation that highly classified documents had been sitting publicly on the internet for weeks.

Those leaked documents, which appeared to catch the administration flat-footed, disclosed a blunt US intelligence assessment of the war in Ukraine, as well as details revealing US intelligence collection on allies. Authorities arrested and charged a 21-year-old Air National Guardsman in connection with leaking the trove of documents. He has not yet entered a formal plea.