Israeli officials in Jerusalem on Wednesday reacted to news of Barack Obama's victory in the US presidential election with a degree of concern.

Israel's leadership from caretaker Prime Minister Ehud Olmert to Foreign Minister Tzipi Livni to President Shimon Peres all offered their warm congratulations to Obama in personal letters and overnight phone calls.

But unnamed officials cited by Army Radio and other Israeli media outlets expressed anxiety that Obama's ascendance will enhance the greatest current existential threat facing the Jewish state: the Iranian nuclear program.

Obama repeatedly stated that he would meet with Iran's leadership without preconditions, a move that Israeli officials fear will give Iran the covering it needs to complete its work on a nuclear bomb without fear of military intervention by Israel or the US.

The officials said they do not see any drastic changes in US policy regarding other Israel-related issues of importance, such as the peace process with the Palestinians and combatting Islamic terrorism in the region.

Israel's largest daily newspaper, Yediot Ahronot, disagreed with that assessment a day before Obama's victory, warning that the Democrat's policy toward Iran would also extend to groups like Hamas.

The Palestinian leadership in Ramallah, too, believes that Obama will alter more than just US policy toward Iran and Iraq, and will be far more forceful than President George W. Bush in extracting territorial concessions from Israel.