The convoy, the agency wrote in a bulletin, “could severely disrupt transportation, federal government, and law enforcement operations through gridlock and potential counterprotests.” 

The warning, sent on Tuesday to federal, state, and local law enforcement officials, and first obtained by Yahoo News, comes as a group of Canadian truckers and others who call themselves the “freedom convoy” have converged in Ottawa, Canada, and shut down traffic on the Ambassador Bridge that connects Windsor, Ontario, to Detroit, the busiest border link for goods moving between Canada and the U.S. 

The protests in Canada began last month to show opposition to vaccine requirements for drivers crossing the border, but they have quickly expanded in scope and focus as popular far-right figures have lent their names to the cause. Politicians like former President Donald Trump and Rep. Marjorie Taylor Greene (R-Ga.) have shown their support for the convoys, while donors have given millions of dollars through crowdfunding sites to support the movement. 

Trump released a statement last week linking the protests to his own personal vendetta against social media platforms like Facebook and Twitter, claiming that the big tech companies were attempting to “destroy the Freedom Convoy of Truckers.”  

The demonstrators are “highly organized, well funded, extremely committed to resisting all attempts to end the demonstrations safely,” Ottawa police chief Peter Sloly told media, adding that a “significant element from the United States” was involved in the funding and organization of their protests. 

The alert from Homeland Security says that “the group intends to start in California as early as mid-February and travel to Washington, D.C., as late as mid-March, reportedly gathering truckers as they travel across the country.” Truckers from the protest in Ottawa may also head to Washington to protest, it adds.

The bulletin does add that for now the protests appear to be “aspirational” as they’re only being discussed online, but Homeland Security officials told Yahoo that this was a very real concern and that they expect the convoy to disrupt traffic and shut down roads. 

“At this time, we have no indication that individuals discussing participating in these activities in the United States are engaged in anything other than First Amendment–protected activity,” the DHS alert said. “Nonetheless, DHS remains concerned that these events could have significant public safety implications or potentially be exploited by ideologically motivated actors to potentially act or encourage others to act violently.”