According to United States' intelligence gained last month, former military chief and head of the Venezuelan Socialist Party, Diosdado Cabello, may have issued an order for Sen. Marco Rubio's (R-Fla.) death, the Miami Herald reported.

Federal authorities were unsure of when the attacks would occur, which prompted additional security details in Miami and Washington, D.C.

Rubio and Cabello have had a public feud with one another. Just last week, Cabello took to Twitter to call Rubio "Narco Rubio."

Rubio responded by reminding Cabello of the nickname he was given: "Pablo Escobar," a name the Venezuelan leader received months ago because of his suspected drug trafficking.

The Department of Homeland Security issued a memo that was law enforcement sensitive but not considered classified. The memo revealed an “order to have Senator Rubio assassinated," but said they had no specific information about how the assassination attempt would be carried out, the Miami Herald reported.

The memo did, however, note that Cabello was critical of Rubio and might have contacted “unspecified Mexican nationals” to carry out the attack.

Since President Donald Trump took office in January, Rubio has advocated for a strong United States response to the Venezuelan government.

For years, the U.S. has investigated Cabello and other high-ranking Venezuelan leaders for suspected drug smuggling, which Cabello vehemently denies.