What is going on with FBI?

After publication of my book Vil Mirzayanov. State Secrets: An Insider's Chronicle of the Russian Chemical Weapons Program, local (Newark, NJ) FBI department started literally to harrass me. First time they came and asked about details in my book. I explained everything. They came second time with same questions. I explained. Right now they want to come again...with someone . This someone probably is CW specialist who wanted to talk to me under the pressure and suprevision of FBI agents. But it is really harrasing if not intimidation! I don't have any pleasure to explain again and again why I wrote my book. Probably FBI as CIA is not happy with my revealations of the Russian secrets. Isn't it strange that for the same reason KGB prosecuted me in Russia 3 years sending to prison twice and right now in USA other agencies started for the beginning to harras me? I am living in USA 14 years and don't feel safe because of these people. Who and what they are protecting by this way? Why they feel themselves so powerful to violate my human rights to live in peace and disturb my private life? Are they above the basics of the US Constitution?