Israel has never had lawful borders. In 1947 the UN partition proposed Israel get 51% of mandate Palestine & the other 49% to the arabs and Jerusalem would be some kind of international entity. In 1949 when the war of independence ended Israel was left with 78% of Palestine + west Jerusalem all of which it annexed after the war. Jordan took the remaining 22% of Palestine & east Jerusalem and that remained the border until 1967 when Israel captured the remaining 22% of Palestine and reunited Jerusalem as it should. If Israel was going to return to the UN proposed border it would mean not only giving the arabs the 22% that it took from Jordan but giving the palestinians an extra 27% of land within the green line. It would mean giving up Jerusalem in full. As the borders from 1949 - 1967 are ceasefire lines only & 1967 - today are ceasefire lines where are Israels lawful borders it has never existed within any. Certainly the borders proposed by the UN is not an option.
Western-backed Syrian rebels say kill foreign Islamic State (Reuters)
from the article: Israel should give up Jerusalem as its capital