I hate to bring this thread back on topic, but I happen to have read some about this guy. The article linked above is a bit misleading. What he is building is basically a German V1 with a modern GPS guidance system. It is a pulse jet engine strapped on the back of a gas tank, guidance system and a space made to hold about 20 kilo’s of what ever you wish. I couldn’t build one myself, but if I wanted to I would just look up the information at the library, then I could.
The guy is what you might call an eccentric backyard inventor who specializes in pulsejets. The point he was trying to make was that a terrorist could do this if they wanted to.
The problem with his concern is that, contrary to what the article above states a pulse jet rocket is not ballistic. In fact its quite slow and it would be blown out of the sky long before if reached a target within the US. Now Canada might be in trouble, that is if some one was actually interested in bombing them. The US has quite a sophisticated defence system against this type of thing.