In a speech about a month ago, U.S. Homeland Security Secretary Jeh Johnson warned of the growing threat of “lone wolf” terrorists. He explained some people may not belong to organizations such as the Islamic State or al-Qaida, but may be persuaded to further their causes by making individual terrorist attacks.

Canadians who were aware of Johnson’s remarks may consider them prophetic. It appears our neighbors to the north have been victimized by lone wolves.

In separate attacks recently, men known to have converted recently to Islam killed two Canadian soldiers. One assault occurred in Quebec, when a man used his car to run down two soldiers, killing one. Police shot him to death.

Then, just days ago, Canada’s capital, Ottawa, came under attack. A man shot to death a soldier guarding a war memorial, then stormed into the Parliament building. He, too, was killed by gunfire.

It goes without saying that the overwhelming majority of Americans view terrorist attacks against our friends and neighbors to the north as attacks on us.

But Johnson is right: Lone wolf terrorists are a growing threat. The question is how to deal with people who may have lived in our communities for years – but then succumb to Islamic terrorist propaganda and become killers. Clearly, an effective strategy for dealing with them needs to be developed.