The U.S.-Canada border is the likely path for terrorists to invade the country, according to top national security experts and Congress' most comprehensive review of America's 19,000 miles of coasts and land borders.

"The nexus between known or suspected terrorists in eastern Canada and the northern parts of the U.S. represent [sic] a significant national security threat," said a new report from the Senate Homeland Security and Governmental Affairs Committee, a conclusion reached as Canada decided to settle 25,000 Syrian refugees by March.

"The border is not secure," Sen. Ron Johnson, the Wisconsin Republican who is chairman of the committee, told Secrets. He included the southern border, where he said that drug cartels are teaming with "potentially Islamic terror organizations."

Wisconsin Sen. Ron Johnson's massive report on U.S. borders points to problems in the north where terror suspects have been arrested. AP Photo

He raised concerns about the rushed refugee plans of new Canadian Prime Minister Justin Trudeau. "It is a concern with the new prime minister, Trudeau, opening up his border to refugees. They can come into America, so I would say that increases our risk," Johnson said.

Unlike the U.S.-Mexico border, the U.S.-Canadian border is mostly just a ditch.

His panel's new 100-page report, show in pdf form at the end of this story, is based on dozens of hearings, interviews and trips, cites terror arrests in Canada and U.S. border states of Islamic State threats and quotes several experts raising concerns about how easy it is for illegal immigrants and terrorists to cross in from Canada.

"Security observers have argued that Canada represents a substantial vulnerability, because it provides immigrant visas to individuals who pose a significant threat," said the report, "The State of America's Border Security."

"Witnesses testified before the committee that if someone gets into Canada, they will most likely be able to enter the U.S."

And for thousands of miles of border, for most there is only a shallow ditch and forestlands to stop them. "There is currently no fencing on the northern border. Instead, the demarcation line between the two countries is often marked by a ditch, approximately six inches deep," says the report.

It offers several details of terrorist attempts and also charts how the U.S. and Canada are working to fight it. Consider this entry about terrorism from page 42:

The nexus between known or suspected terrorists in eastern Canada and the northern parts of the U.S. represent a significant national security threat. Communities in Minnesota and New York, which are adjacent to Ontario and Quebec, have recently experienced apprehensions of individuals on terrorist charges. For example, on November 26, 2014, two men in Minneapolis, Minnesota were charged with recruiting and conspiring to provide support to ISIL. Similarly, on September 17, 2014, a man in Rochester, New York was arrested on similar charges after the FBI provided evidence showing that he attempted to recruit fighters and funds for ISIL.

Just a small hop across a ditch to reach the U.S. from Canada.

And it's not just a northern border problem. Johnson said the highly trafficked U.S. border with Mexico is also a pathway for Islamic terrorists, especially as they team up with drug cartels that have carte blanche on their side of the line.

Those cartels "are also combining with transnational criminal organizations, potentially Islamic terror organizations," he said.

Johnson in his report steers clear of the heated presidential campaign rhetoric on how to handle the border and notes that "it's not a war zone."

Solutions for the southern border include development of a guest worker system, a new campaign against drugs, and more efforts to secure the border. He also talked favorably of a recent Bush-era campaign to send those caught at the border home immediately, an effort that led to a drop in illegal border crossings.

Up north, he wants a "threat analysis" to see what more can be done to stop terrorists from slipping in. "Start now," he said.

Paul Bedard, the Washington Examiner's "Washington Secrets" columnist, can be contacted at pbedard@washingtonexaminer.com.