What is the source of this concept and what are the halachic parameters of yad yisrael takifa al hagoyim? and is this concept applicable today in light of the geopolitical situation in Israel? And what are the ramifications if it is?

This is a very broad topic, well beyond the scope of this concise website. I'll just direct you to the following article (espcially the final chapter) which deals with your question: https://he.wikisource.org/wiki/%D7%97%D7%91%D7%9C_%D7%A0%D7%97%D7%9C%D7%AA%D7%95_%D7%90_%D7%96