WASHINGTON — A warning from the Justice Department could force one of the world’s largest marijuana festivals to press on without the very herb it celebrates.

Nevada’s Moapa Paiute Tribe is scheduled to host the High Times Cannabis Cup this weekend outside Las Vegas. But in a Feb. 16 letter, a federal attorney reminded the tribe’s chairman that while Nevada law permits the recreational use of marijuana, federal law does not, as the Reno Gazette-Journal first reported.

“I am informed that the tribal council is moving forward with the planned marijuana event referred to as the 2017 High Times Cannabis Cup because it is under the impression that the so-called ‘Cole Memorandum’ and subsequent memoranda from the Department of Justice permit marijuana use, possession and distribution on tribal lands when the state law also permits it,” U.S. Attorney Daniel Bogden wrote in the letter, obtained by the Gazette-Journal. “Unfortunately, this is an incorrect interpretation of the Department’s position on this issue.”

The pair of memoranda Bodgen references direct U.S. district attorneys to consider state laws in their enforcement of marijuana and consult with tribal governments on a case-by-case basis. But as Bodgen wrote, “nothing” in them “alters the authority or jurisdiction of the United States to enforce federal law in Indian Country or elsewhere.”

The threat of interference at the festival is among the first signs that the Trump administration is serious about cracking down on recreational marijuana, despite the president’s campaign pledge to respect states’ rights on the issue. During a press conference last week, White House press secretary Sean Spicer linked recreational pot use to the nation’s opioid crisis and said he expects to see greater enforcement by the Department of Justice under President Donald Trump.

Andres Stapff/Reuters A judge checks a marijuana sample during a judging session of Uruguay's second "Cannabis Cup" at a hotel in downtown Montevideo June 22, 2013.

The Cannabis Cup, which was founded nearly three decades ago and is held annually in Amsterdam, is the “world’s leading marijuana trade show, celebrating the world of ganja through competitions, instructional seminars, expositions, celebrity appearances, concerts and product showcases,” according to its website.

The Las Vegas event, scheduled for March 4-5, was set to feature all the usual competitions and samplings, and serve as a celebration of Nevada’s recent legalization of recreational cannabis. But in a last-minute memo, event producer High Times urged vendors and attendees not to indulge.

“[F]ederal authorities have intervened directly with our host venue, the land of the Moapa Band of Paiutes,” the cannabis-centric magazine wrote. “Vendors, guests, performers and attendees are advised to comply with all local, state, and federal laws regarding the use and distribution of cannabis and cannabis related products.”

High Times added that for the weed industry to earn legitimacy and acceptance, it must follow established laws.

“High Times will continue to stand up for our civil liberties and advocate for our inalienable rights to cultivate and consume cannabis,” it wrote. “We urge you to join us.”

Seth McConnell via Getty Images A man exhales marijuana smoke during the High Times Cannabis Cup at the Denver Mart in Denver, Colorado on April 19, 2015.

The tribe’s chairman told the Gazette-Journal he is working with the U.S. Attorney’s Office in Nevada in hopes of resolving the conflict.

“To us, we’re looking at it as utilizing our sovereignty,” Daboda told the publication. “The tribe is promoting it as a vendors’ crafts, food and concert event. We’re not promoting the distributor or selling [marijuana].”

A total of 28 states have legalized marijuana for medical purposes, and eight states and the District of Columbia have legalized recreational use. But marijuana remains illegal under the federal Controlled Substances Act. While in office, former President Barack Obama urged federal prosecutors to refrain from targeting state-approved operations. After Washington and Colorado green-lighted recreational marijuana in 2012, Obama said the federal government had “bigger fish to fry.”

The Trump administration, however, appears set on taking a more forceful approach. Along with Spicer’s recent marijuana comments, Attorney General Jeff Sessions, a longtime opponent of marijuana use, has hinted at a potential federal crusade against recreational cannabis.

“My best view is that we don’t need to be legalizing marijuana,” he said Tuesday.