The migrant surge crippling the U.S. southern border has made its way north as one Vermont sector endured an 846% spike in migrant encounters from the same time period in 2022. 

But one Border Patrol representative in the thick of the matter says there are more actors to blame than just President Biden and his administration.

Sean Walsh, president of the Swanton sector of the National Border Patrol Council, called out Canadian Prime Minister Justin Trudeau Tuesday for "allowing" the crisis to worsen with his country's lenient travel policies.

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"They're not saying anything," Walsh told "America's Newsroom." "They're allowing it to happen. The visas in place, they are allowed to travel a lot easier. They fly into Montreal, Ontario, and you name it across Canada, and these cartels and smuggling organizations are making money hand over fist."

"And despite the freezing temperatures, despite the weather conditions, they're bringing in these people across," he continued. "There's no one in the field to apprehend them."

The former Border Patrol chief for the Yuma, Arizona, sector, Chris Clem, explained that "electronic travel authorization allows [migrants], basically visa-free, to fly in from Mexico to Canada, which means now they have access to move about Canada freely. And then at that point, they're coming in."

This comes as officials recorded 367 migrant encounters in Vermont's Swanton sector in January 2023, compared to just 344 encounters in the last 12 Januarys combined. 

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But federal agents have faced unprecedented staffing shortages in recent years, prompting cartels to exploit what some critics call a porous border to the north as many agents have been diverted south. 

"For the last two years, agents have been deployed from the northern border to the southern border or virtually processing illegals down there, and this has led to large parts of the border being unsecured, unguarded," Walsh said. 

"It's scary to see how the cartels were able to exploit the borders because of the policies that are in place," he continued. "The lack of manpower is a large part of why these cartels were able to start to use the northern border the way that they're they're using it now."

Fox News' Casey Stegall previously reported that the surge at the northern border has prompted agents to return to Vermont to mitigate the unparalleled number of encounters that critics argue was due to the lack of agents. 

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Walsh argued the surge has escalated to a degree that officials are unaware of "what's coming through" the U.S.-Canada border because of the strained resources. 

"It's very similar to the southern border where… the majority of them are being released into the country, some of them are being held," Walsh said. "And that's one of the issues that we're having, is we already have a low amount of agents in the field, and when we arrest and apprehend somebody, these agents are going back to the office and processing these individuals, leaving the border unsecured again."

"We really don't even know what's coming through our borders because we don't have the agents in the field."

Fox News' Adam Shaw and Elizabeth Heckman contributed to this report.