Canada is seen across the United States border near Havre, Montana, United States, November 20, 2015. Picture taken on November 20, 2015. REUTERS/Lucy Nicholson

By Tim Reid

HAVRE, Montana (Reuters) - Standing two feet from Canada on windswept Montana prairie land, U.S. Border Patrol agent Andrew Herdina looks out over a line of crooked old fence posts with no wire between them -- the international border.

"If somebody is set on doing it, there are plenty of opportunities to cross this border," said Herdina, surrounded by a vast expanse of prairie grass where there were no border posts, or checkpoints, or any visible signs of security.

With U.S. security concerns heightened following the attacks in Paris claimed by Islamic State, the relatively porous state of America's northern border has attracted little attention as politicians, mostly Republicans, have attacked President Barack Obama's plans to allow in 10,000 Syrian refugees.

But in Montana, which shares a 500-mile (800-km) border with Canada, border agents and some residents say they are concerned about Ottawa's plan to bring in 25,000 Syrians by year-end, even though the government there insists its screening will be thorough and there are limited indications that militants may be seeking to use refugee status to cross borders.

The world's longest shared land border attracts a fraction of the U.S. attention and security resources taken up by the much shorter southern border with Mexico, which is patrolled by 18,000 U.S. border agents compared to 2,200 in the north.

The National Border Patrol Council, the border patrol union, says at least another 2,000 agents are needed on the Canadian border, which runs 5,500 miles from Alaska to Washington State and Maine. Herdina says the most effective tool in tracking illegal border crossers is not the border agents or surveillance airplanes; it’s the roughly 100 ranchers who span Montana's border with Canada.

"They are our best asset," said Herdina, who is vice-president of the Montana branch of the union.

Last year, one rancher called the border patrol to report two strangers on his land, Herdina said. They were two Guatemalans who had crossed the border illegally.

Janas Strauser, owner of 66 Ranch on the border, said: "The people up here will report people who cross the border. The ranchers and farmers call them in."

While the border patrol union has a stake in securing more jobs and funding, its view was supported by a 2011 report by the Government Accountability Office, a non-partisan congressional watchdog, which found that only 32 miles of the border was properly secure and that the security risks were genuine.

“The terrorist threat on the northern border is higher (than on the Mexican border), given the large expanse of area with limited law enforcement coverage,” the report said.

The White House referred questions about the security of the northern border to the Department of Homeland Security (DHS).

The DHS referred Reuters to its website, which notes that the number of U.S. agents on the northern border has jumped from just 340 in 2001 and that its technological capabilities have "greatly improved." The U.S. Customs and Border Protection (CBP) says it now deploys fixed and rotary-wing aircraft equipped with sensors, thermal camera systems, remote videos and drones to help secure the border.

"There is no way you can make it totally secure," said Andrew Finn, program associate with the Canada Institute at the Wilson Center, a Washington DC-based think tank. "You always have to think about the terrorist threat, although the vetting process for refugees into Canada is quite thorough.”

"HYSTERIA AND EXAGGERATION"

Obama has denounced the “hysteria and exaggeration of risk" over Syrian refugees, who already face a rigorous U.S. vetting process. Most of the attackers in Paris are believed to be have been European residents rather than new immigrants, though authorities are investigating if one traveled as a refugee.

Newly elected Canadian Prime Minister Justin Trudeau is standing by his pledge to allow 25,000 Syrian refugees into Canada by Jan. 1. Current and former Canadian security sources told Reuters last week that corners would have to be cut on security screening due to the accelerated process.

Canada experienced two attacks by radical Muslims in 2014, and reluctance in provinces such as Quebec to accept Syrian refugees is raising concern of a growing social rift with Muslim minorities.

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