Well, I don't know how to know if the real "Al Qaeda" did declare jihad as opposed to someone impersonating a member of Al Qaeda. But there is no question that this Jihad against America and Christians is preached over the internet, television and radio waves in middle eastern countries. In fact, the website
TheirOwnWords.com does an excellent job of documenting this kind of hate speech.
TheirOwnWords compiles English translations of clips from public television in countries such as Iran so that Americans can understand how violent radical jihadists are. Americans do not realize what radical jihadists say about America.