The counter terrorism efforts in detecting terrorist threats

I wrote a few days ago about the terrorist attack and Canada and how it has affected that country with the government there saying that they will upgrade their anti terror laws and one news came out that the two people were known to Canadian authorities but they did not share this information with U.S. authorities because of the privacy laws and court rulings in Canada against doing that and I was thinking what? I can understand that there are some privacy issues but if a person is a known threat to a country, would it be not appropriate to inform the U.S. and other countries that if by any chance you see this guy in your country, be careful and keep them under surveillance. I know that everybody wants to gang up on the U.S. to intruding on everybody’s privacy but to its credit if it has not done so there would have been many terrorists attack on the U.S. soil. And nobody in the world can deny this fact that only the U.S. has the capability and the resources to detect terrorists’ threats and prevent them more successfully than any other country. I know that even this capability there have been terrorists attack in the U.S. and other country and nobody can be hundred percent vigilant against it but only with the cooperation between countries, the threats can be minimized. And with some in the security apparatus of the U.S. as saying that the northern border with Canada is highly susceptible to terrorists activities, it is time government of other countries set aside this privacy issue of their citizens aside to some extent and share intelligence with U.S. and other countries so that they avert any possible terrorists attack in their respective countries.