It is not a matter of some groups "deligitimizing" Israel. It is Israel that has deligitimized itself -because it believes that it has all the influence in the USA that it wants and needs. This "allows" it to do whatever crosses its political class' mind with regard to the Palestinians. Yes, the sky is its limit - sadly, until history catches up with that country. And then???????????
U.S.-led coalition conduct 23 air strikes against ISIS in Iraq and Syria (Reuters)
from the article: Think tank: Israel faces global delegitimization campaign