OTTAWA, TORONTO -- Security around Parliament Hill has increased since the day five years ago that terrorists killed thousands in the United States but it would still seem possible to drive a van full of explosives to the base of the Peace Tower.

At the Wellington Street entrance to the buildings that are the central hub for the Canadian government, a lone RCMP vehicle guards -- but does not block -- the front gate.

Federal security forces will not discuss the steps taken to make Parliament Hill more secure since the attacks of September, 2001, opened the world's eyes to the destructive power of terrorism. So it is possible that there are invisible measures that would prevent a speeding vehicle from driving through the open entryway.

"There is no question, if you wanted to do an attack on these buildings from the outside of the building it's relatively easy to do that," said Joe Comartin, the public safety critic for the New Democrats.

The police are not talking publicly about what sites were allegedly being targeted by the 17 people now who have been charged with participating in a terrorist group and an assortment of other crimes. But sources say the Peace Tower was on the list.

Alternate sites for the House of Commons have already been chosen in case a terrorist attack knocks out the Centre Block of the Parliament Buildings, federal officials told The Canadian Press yesterday.

At least one temporary and one long-term facility have been identified as part of Canada's efforts to ensure that its democratic institutions can withstand any violence.

Meanwhile, the number of layers of security has increased since 9/11. Contractors doing business on the Hill must obtain clearance from a government department that alerts the RCMP in advance of their arrival. All of the people entering the site in a vehicle must be cleared by authorities. And cars and trucks are routinely searched.

In Toronto, where the CN Tower and the Toronto Stock Exchange were said to have been selected as additional targets by the group in custody, there was a mixed reaction to the revelation of the plot.

At the CN Tower yesterday, a steady stream of tourists continued up the tower without delays. CN Tower general manager Jack Robinson said authorities had not contacted him about the alleged plot, and as far as he knew, the tower wasn't a target. None of its security measures had been altered because of the alleged terror plot, he said.

Visitors and employees to the Rogers Centre in Toronto, home to many major concerts and the Blue Jays baseball team, were affected by new security measures yesterday.

At the entry to the parking garage beneath the building is a new security post, all cars entering were required to stop and open their trunks for inspection.

Blue Jays president and CEO Paul Godfrey said the decision was made to boost security because of the terror raids; however, police have not indicated that the stadium is under threat. The purpose of the inspections, he said, was to make the stadium's security team more visible.

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