Did Joe Biden really trip over his words on Iran?

US vice president Joe Biden is notorious for speaking out of turn. His latest mishap occurred in Israel. There, he gave us to understand that the US wouldn't stay Israeli's Netenyahu's government's
if Jerusalem thought its security threatened by Iran by bombing Tehran's underground nuclear facilities. Immediately president Barack Obama [BHO] riposted by saying the US won't give Israel the green light. His predecessor George W Bush, more hawkish than BHO, put a damper on Israel's ardour, too, if anyone has forgotten it.
Nevertheless, it is reasonable to suggest that Biden didn't commit another gaff. BHO took a reasonable approach to the brouhaha in the aftermath of Iranian elections, with its 'blitzkrieg' results handing a questioned victory to the incumbent, president Mahmoud Ahmadi Nejad. BHO risked the wrath of crumbling Republican party and some within his own party's ranks, who thought him soft. The US president plays a good game of poker so his responses to the turmoil in post elections Iran was measured and graduated according to the events on the ground. Which proved his instincts were on the money.
Saying this, of late, an impatient tone has crept into the White House's language on Iran. Although Tehran may want to engage Washington, it is going to proceed on its own terms and at its own pace.
BHO had shaped his opening to Iran by saying he was extending an opening hand not a closed fist. His flat hand has not been readily seized by Tehran yet. Hence the growing impatience and edgy words. Now into this atmosphere comes the report of Biden's comments. It is a veiled warning that Iran would be better where it to enter into direct talks with the US than suffer the 'existential threat' of war with Israel.