Diosdado Cabello is Venezuelan President Nicolas Maduro’s right-hand man. Cabello frequently goes on the attack against Maduro’s opponents both at home and abroad. Today the Miami Herald reports intelligence sources believe Cabello may have issued an order to have Senator Marco Rubio assassinated.

The death threat was outlined in a memo to several law enforcement agencies disseminated last month by the Department of Homeland Security. The memo, designated “law enforcement sensitive” but not classified, was obtained by the Miami Herald.

The memo revealed an “order to have Senator Rubio assassinated,” though it also warned that “no specific information regarding an assassination plot against Senator Rubio has been garnered thus far” and that the U.S. had not been able to verify the threat. That Cabello has been a vocal Rubio critic in Venezuelan media was also noted, a sign federal authorities are well aware of the political bluster complicating the situation.

According to the memo, Cabello might have gone as far as to contact “unspecified Mexican nationals” in connection with his plan to harm Rubio.

The details of the plot may not have been verified, but the threat is being taken seriously enough that Rubio is being given an extra security detail in Washington, D.C. and in Miami. Cabello and Rubio have recently exchanged words on Twitter. Rubio said this last week:

Fact that Narco leader @dcabellor annouced #6Aug military rebellion & govt response shows who's in charge of security forces in #Venezuela

— Marco Rubio (@marcorubio) August 6, 2017

The reference to Cabello as a “Narco leader” is meant to suggest he is profiting from trafficking in Venezuela. Cabello responded with two tweets, one of which referred to “Narco Rubio”

Narco Rubio, alias @marcorubio, lo peor de la política imperial, aparece como el defensor de los terroristas que atacaron Fuerte Paramacay.

— Diosdado Cabello R (@dcabellor) August 6, 2017

Google translate renders that as “Narco Rubio, alias @marcorubio, the worst of the imperial policy, appears as the defender of the terrorists who attacked strong Paramacay.” Today, Cabello retweeted a response to the Miami Herald assassination story. The tweet reads, “The Lord @marcorubio in addition to being a Narco is an evil creator of false positives! Now they say q @dcabellor wants to assassinate the NarcoRubio.” You get the impression that Rubio calling Cabello a “Narco leader” really got under Cabello’s skin.

The information on Cabello’s ties to narco-trafficking come from Cabello’s former bodyguard, Leamsy Salazar, who defected to the U.S. and was reportedly cooperating with federal prosecutors. From the Wall Street Journal:

U.S. prosecutors are investigating several high-ranking Venezuelan officials, including the president of the country’s congress, on suspicion that they have turned the country into a global hub for cocaine trafficking and money laundering, according to more than a dozen people familiar with the probes…

A leading target, according to a Justice Department official and other American authorities, is National Assembly President Diosdado Cabello, considered the country’s second most-powerful man.

Leamsy Salazar, who had previously worked for late President Hugo Chávez’s security detail, is currently in Washington, where he is expected to provide witness testimony implicating Mr. Cabello in organizing cocaine-smuggling operations controlled by Venezuela’s military, two people familiar with the matter said.

Last year the U.S. indicted two Venezuelan generals, both members of the country’s anti-drug agency, with being drug traffickers.