I see the article went completely over your little head so allow me to summarize it for you:

The borders of what constitutes the state of Israel today ie. the territory east of the river Jordan to the Mediterranean Sea were established by the League of Nations in 1922 and nothing that has happened since has legally modified these frontiers.

We continue to hear the term "illegal", but "legal and illegal" has to be more that political desires and interests. It has to refer to law.