If you go to a Internet search engine or in my case, Google and search for CIA KGB assassination gadgets .. these are just a couple of the sites that show the scary stuff and subtle and not so subtle ways of taking out the other guy.
Kalugin-KGB article from CNN
or at
Military Intelligence, A sloughful of links on varied topics and Towards the bottom of the page are some gadgets,
and from the
National Geographic.
Thanks.