From the Israeli newspaper Ma'ariv (in Hebrew, translated by MW contributor Shmuel):
Israel: We Won't Give Advance Notice of Attack on Iran
Sunday Times reports that Israel told Chairman of Joint Chiefs of Staff it would give only twelve hours' warning, for fear that Obama would try to prevent [an attack].
Maariv NRG, 22/1/12
Israel informed Chairman of Joint Chiefs of Staff Martin Dempsey, during his visit over the weekend, that it would not request US authorisation for an attack on Iran, and that it would give only twelve hours warning before launching such an attack, according to this morning's Sunday Times.
According to the report, Netanyahu does not trust Obama and believes the President might do everything [in his power] to prevent an attack if informed in advance, for fear of rising oil prices in an election year.
Recently, Obama called Netanyahu asking for clarifications regarding [a possible] attack [against Iran]. According to the Sunday Times report, the conversation was strained, and the Prime Minister explained his position, insisting that he would refuse to share details with the White House, should such an attack be launched. According to the report, the differences between the two sides increased further in the wake of Dempsey's meeting with Defence Minister Ehud Barak at the weekend.
Times reporter Uzi Mahnaimi adds that outwardly, Israel and the United States are trying to downplay the crisis, but the two countries would appear to be on a collision course.
For example, Dempsey claimed that Israel and the United States had agreed to postpone the scheduled joint military exercise and that the postponement would serve [the interests of] both sides. The fact is however, a defence source told the Sunday Times, that this is false. "We were shocked", said the source. "The exercise had been planned for two years."
I couldn't find the Sunday Times article on their website in front of the paywall, but please post it below in the comments if you have it.