I don't know about international laws regarding flights passing other countries airspace. But if the US would force down a Russian civilian airplane, to perform an arrest after the request to perform this arrest on Russian soil was denied, I guess that would cause some major diplomatic trouble between the US and Russia. I doubt it would be solved by summoning the ambassador.
I think you'd find the international security area at the airport is still sovereign soil; the country just, for obvious practical reasons, doesn't insist on people going through immigration and customs in order to transit through.
