I am not a patent attorney. However, many associates in Japan want me to clarify what is going on in the U.S. (Please don't laugh and make sarcastic comments.) In one case:
If a Japanese firm is sued products sold in the US, but they believe they are not infringing, where would the case be tried?
If a Japanese company sues a US firm, where would the case be tried?
Patent Venue: Cyberspace does not Expand Place of Business
https://patentlyo.com/patent/2017/09/patent-cyberspace-business.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed:+PatentlyO+(Dennis+Crouch's+Patently-O)