The House Democrats' top investigators on Saturday asked the director of National Intelligence to conduct a review and damage assessment of the boxes of highly classified information seized by the FBI this week from former president Donald Trump's Mar-a-Lago estate.

The letter was sent to National Intelligence Director Avril Haines by House Oversight Chairwoman Carolyn Maloney, D-N.Y., and House Permanent Select Committee on Intelligence Chairman Adam Scahiff, D-Calif., and cites the search warrant cataloguing the classified documents of various levels of sensitivity found at Mar-a-Lago.

"Former President Trump's conduct has potentially put our national security at grave risk," the two wrote, asking also for a classified briefing on the assessment as soon as possible. "This issue demands a full review, in addition to the ongoing law enforcement inquiry."

The two also voiced concern that the FBI is looking in part at highly classified documents related to nuclear weapons, as first reported by The Washington Post.

"If this report is true, it is hard to overstate the national security danger that could emanate from the reckless decision to remove and retain this material," the letter states.

On Monday, the FBI executed a court-authorized search warrant at Trump's Florida home and removed around 20 boxes of documents, including "various classified TS/SCI documents," according to a written inventory. That translates to top secret/sensitive compartmented information, a highly classified category of government secrets, and top-secret papers.

The warrant also said that federal agents were investigating the potential violation of three different federal laws, including a part of the Espionage Act outlawing gathering, transmitting, or losing national defense information. The warrant also cites the destruction of records and concealment or mutilation of government material.

Schiff and Maloney write that in accordance with Intelligence Community directives issued by the DNI, a damage assessment is necessary "to evaluate actual or potential damage to national security resulting from the unauthorized disclosure or compromise of classified national intelligence."

The boxes recovered by the FBI come after months of back-and-forth between investigators and representatives from Trump's team following the end of the Trump presidency. The National Archives first recovered 15 boxes and documents, mementos and classified information belonging to the U.S. government in January of this year from Mar-a-Lago before the matter was referred to the Department of Justice.

Material about nuclear weapons is especially sensitive and usually restricted to a small number of government officials, according to experts.

An unauthorized disclosure of classified information or U.S. weapons could provide helpful information to adversaries seeking to build ways of countering U.S. nuclear systems. A damage assessment will evaluate the extent of the damage caused by an unauthorized disclosure.

The former president previously disclosed highly classified intelligence to Russian officials in 2017 that jeopardized a critical source of intelligence on the Islamic State.