jurisdiction - noun the official power to make legal
decisions and judgments.
No sane justice or legislator would assert that establishment of laws, and the prosecution there of; is not apart of “jurisdiction” and part of the authority of Congress as established by the Constitution. Thus, those that are subject to the laws of Congress are subject under the jurisdiction of Congress. There is no question in US or even international law that the US Congress has jurisdiction over the lands and territories of the US.
As currently written, the 14th is very clear that it applies (grants citizenship) when:
1) the person in question is born or naturalized within the US
- and -
2) subject to the jurisdiction of the US
If you don’t like it (I don’t), then change it.
Are you subject to the jurisdiction of the US when in Germany?
No citizen of one country is a member of the territory or sphere of authority of another country. One may visit, but that visit doesn't make you a member of that society. That is why there are embassies and passports... to service the citizens of foreign sovereigns.
Your argument, and the argument of all jus soli proponents is one of schizophrenia... in making the argument that location of birth--and not the allegiance of the parents--takes precedence, you undermine the rest of international law and authority. Foreign diplomats who have children while on duty in our country are not birthing US citizens. The same is true of those who illegally enter.