Harper, in London to attend the funeral of former British prime minister Margaret Thatcher Wednesday, appeared to take issue with Trudeau’s suggestion to search out the “root causes” behind Monday’s devastating attack.

“When you see this type of violent act, you do not sit around trying to rationalize it or make excuses for it or figure out its root causes,” Harper told reporters.

“You condemn it categorically, and to the extent you can deal with the perpetrators, you deal with them as harshly as possible.”

http://www.thestar.com/news/canada/2013/04/17/stephen_harper_and_justin_trudeau_exchange_barbs_over_boston_bombing.html