The ''red line'' would be the point at which a military strike would be needed to stop Iran developing a nuclear bomb. From the viewpoint of a vulnerable Israel, it's best if the US launches the attack. But if it falls to Israel to do it, it still craves superpower support.
On the same day, apparently sensing Netanyahu's rising impatience, the commander of Iran's Revolutionary Guard, Mohammad Ali Jafari, warned that ''nothing would remain'' of Israel if it were to attack Iran. US bases would also be targeted, he said.
The US President, Barack Obama, refused to be panicked. In the past week or so the world saw that ''finally, Israel's Prime Minister blinked,'' as the Financial Times put it.
Netanyahu continued to talk about the danger of Iran's nuclear program. He even stood on the podium before the nations of the world assembled at the United Nations General Assembly last week holding a crudely alarmist sketch of a cartoon-style round bomb with a lit fuse and a red mark drawn to illustrate the concept of a red line.
But his speech indicated that the crisis point for confronting Iran with force had moved into next year, beyond the US election.
Israel itself is deeply divided on the matter. Not only the public, but the political and security elites are divided, too.
While Netanyahu and his Defence Minister, Ehud Barak, are seen as the hawks most eager to strike Iran, most of the security establishment of the country argues that an attack now would be ill-judged.
Even Netanyahu's own 14-member security cabinet is reported to be divided.
One point of consensus between just about everyone in the US and Israel is that a military strike on the Iranian weapons program, buried deep underground, would only delay, not destroy, Iran's campaign to build the bomb.
So the key question for Israel is not whether it will eventually confront a nuclear-armed Iran, but whether it will have the US by its side when that day comes.