When it comes to the threat of terrorism, the Canadian border is a bigger problem than the Mexican one, a U.S. security official says.

Customs and Border Protection Commissioner Alan Bersin said he is concerned that potential terrorists are exploiting Canadian loopholes to gain entry to the United States.

"We have had more cases where people who are suspected of alliances with terrorist organizations, or have had a terrorist suspicion in their background - we see more people crossing over from Canada than we have from Mexico," he said during in his testimony to the U.S. Senate this week.

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The remarks will grate on Ottawa officials, who frequently try to persuade U.S. counterparts that the terrorist threat emanating from north of the border is not that bad.

Last year, U.S. agents are said to have arrested 450,000 migrants crossing from Mexico, where drug wars are resulting in mass murder. This compares to about 7,500 inadmissible people caught crossing the Canadian border.

Despite these overall numbers, Mr. Bersin said that it is "commonly accepted that the more significant threat" to the United States comes from the north.

One reason for that perception might be the sheer number of people being flagged in Canada as terrorist threats, a practice that leaked State Department memos are now calling into question.

Three leaked memos, released by WikiLeaks to the CBC Wednesday, show that U.S. diplomats used Canadian information to place several never-arrested suspects - including one paid police agent - on U.S. blacklists.

In 2006, the RCMP arrested 18 terrorism suspects in a case that garnered 11 convictions. Yet a total of 27 people were secretly placed on U.S. watch lists, according to a cable from 2009. "The Canadian authorities have not arrested nine other individuals involved in the Toronto 18 case," the cable reads.

Oddly, one of nine is Mubin Shaikh, a paid police infiltrator who was - at the time the cable was sent - giving public testimony about how he had infiltrated the wider group on behalf of police.

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"Clearly it's a mistake," Mr. Shaikh said in an interview. He argued that most people who are on watch lists belong on the lists, and that he has "compete confidence" in Canada's ability to safeguard intelligence sources.

A February, 2010, State Department cable shows 12 Canadians were red flagged for being "known associates" of Hiva Alizadeh, an Iranian-Canadian who was arrested in Ottawa last August on bomb-plot charges. Only two alleged co-conspirators were charged.

Watch lists are cautionary by nature, and compiled by authorities who work to far lower thresholds than counterterrorism police.

In his Senate testimony, Mr. Bersin also complained that Canadian and U.S. officials do not share "No Fly" lists.







