Two crossings on the U.S.-Canada border, including the busiest, have been partially blockaded, and demonstrators were attempting to block a highway to a third.

"They're essentially putting their foot on the throat of all Canadians," Bill Blair, Canada's minister of emergency preparedness, said Wednesday. "It can't be allowed to persist."

Meanwhile, the Department of Homeland Security is warning that U.S. truckers are potentially planning to block roads in major metropolitan areas in protest of vaccine mandates, and that the protest activity could impact the Super Bowl in Los Angeles this Sunday as well as President Biden's State of the Union address March 1, according to a copy of the bulletin obtained by The Washington Post.

The DHS has distributed a bulletin to law enforcement agencies warning that a convoy of protesting truckers will potentially begin in California as early as mid-February and arrive in D.C. as late as mid-March. Truckers from Canada may potentially join the convoy as it travels eastward, the DHS warned.

The bulletin was first reported by CBS News.

In a statement, DHS spokesperson Angelo Fernandez confirmed the department "is tracking reports of a potential convoy that may be planning to travel to several U.S. cities."

"We have not observed specific calls for violence within the United States associated with this convoy, and are working closely with our federal, state, and local partners to continuously assess the threat environment and keep our communities safe," the statement read.