You know there are court systems which exist outside the USA right? If I commit a crime in Russia I do not suddenly get a right to a trial in the US.
Actually, if an American citizen commits the crime of treason in any place in the world, they are subject to USA law and punishable in US courts. If you commit the crime of treason against the USA while in Russia you are subject to extradition and conviction in USA courts. It happens to the spies against the USA all the time. The problems are with extradition when the hostile countries refuse.