Originally Posted by
MH86
Because my father's name (Smith) is included in my first name, it does not mean that it should be considered as a middle name.
And I don't have any documents that says that (Smith) is a middle name. And the best proof is my passport. It does not consider it as a middle name, only a surname and Given name(s).
Thank you very much for your kind reply

As far as I know,
no-one has a document that defines what is a middle name. It's a matter of what the person applying for that document fills in on the application.
Stop obsessing about this. You won't convince an American authority to follow a Scandinavian perspective on naming practices.
Either put "Johan Smith" or "Johan" as your first name. I don't think it will make a scrap of difference. Once you have got your ESTA (which will happen in a matter of seconds, as long as there is no reason for further investigation, such as a previous criminal conviction) print it out and carry it with you.
Try putting "Johan Smith" as your first name when doing your on-line application. If that is accepted, then you are OK. If that is not accepted, just put "Johan" in that field.
The ESTA is compared with your passport, not your ticket or boarding pass. Most of the time, when the immigration official scans your passport he/she will see that there is an ESTA attached to that passport and they will not even ask to see your printout, your ticket, or your boarding pass.