For the first time in history, FBI agents have raided the home of a former U.S. president.

In a message released today, Donald Trump said that his Mar-a-Lago estate in Palm Beach, Florida is "under seige".

He also said that agents broke into his safe.

It came on the 48th anniversary of the day that Richard Nixon announced his resignation as president. 

Trump  described what  was happening at his home as the "weaponization" of the justice system by radical-left Democrats.

"Nothing like this has ever happened to a President of the United States before," the ex-president continued. "After working and cooperating with the relevant Government agencies, this unannounced raid on my home was not necessary or appropriate."

The FBI must present evidence before a judge in order to obtain a warrant to enter someone's home. The head of the FBI, Christopher Wray, is a Trump appointee.

The New York Times has cited two unnamed sources in reporting that the search was in connection with boxes of classified documents that Trump allegedly brought to Mar-a-Lago from the White House.

A former acting solicitor general in the Obama White House, Neal Katyal, told MSNBC's Laurence O'Donnell that once agents enter a home with a search warrant, they can seize any documents that might point to the commission of a crime, even if it's unrelated to the investigation at hand.