The undertaking, part of a “Jerusalem Declaration” crowning Biden’s first visit to Israel as president, followed his telling a local TV station that he was open to “last resort” use of force against Iran – an apparent move toward accommodating Israel’s calls for a “credible military threat” by world powers.

Washington and Israel have separately made veiled statements about possible preemptive war with Iran – which denies seeking nuclear arms – for years. Whether they have the capabilities or will to deliver on this has been subject to debate, however.

Thursday’s statement, released to the media ahead of a formal signing ceremony, reaffirmed U.S. support for Israel’s regional military edge and ability “to defend itself by itself”.

“The United States stresses that integral to this pledge is the commitment never to allow Iran to acquire a nuclear weapon, and that it is prepared to use all elements of its national power to ensure that outcome,” the statement added.

There was no immediate comment from Tehran.

In 2015, it signed an international deal capping Iranian nuclear projects with bomb-making potential. In 2018, then-U.S. President Donald Trump quit the pact, deeming it insufficient, a withdrawal welcomed by Israel.

Iran has since ramped up some nuclear activities, putting a ticking clock on world powers’ bid to return to a deal in Vienna talks. Israel now says it would support a new deal with tougher provisions. Iran has balked at submitting to further curbs.

“The only thing worse than the Iran which exists now is an Iran with nuclear weapons and if we can return to the deal, we can hold them tight,” Biden told Israeli TV on Wednesday.

EYES ON SAUDI ARABIA

Beyond enhancing the allies’ sense of deterrence and mutual commitment, the statement’s power-projection may also offer Biden a boost when he continues on to Saudi Arabia on Friday. Riyadh has its own Iran worries, and Biden hopes to parlay that into an Saudi-Israeli rapprochement under U.S. auspices.

Earlier on Thursday, Biden told reporters he and Lapid had discussed “how important it was, from my perspective, for Israel to be totally integrated into the region”. Lapid, in turn, deemed Biden’s Saudi trip “extremely important to Israel”.

Some Israeli as well as Gulf Arab officials believe the nuclear deal’s sanctions relief would provide Iran with far more money to support proxy forces in Lebanon, Syria, Yemen and Iraq. They are also skeptical about whether the Biden administration will do much to counter Iran’s regional activities.

A U.S. official, asked if Thursday’s declaration was about buying some time with Israel as Washington pursues negotiations with Iran, said: “If Iran wants to sign the deal that has been negotiated in Vienna, we have made very clear we’re prepared to do that. And, at the same time, if they’re not, we will continue to increase our sanctions pressure, we will continue to increase Iran’s diplomatic isolation.”

A senior Israeli official described the threat of military action as a means of avoiding war.

“(It) is a guarantee that the diplomatic, economic and legal efforts against Iran will be effective,” Defence Ministry director-general Amir Eshel told Israel’s Kan radio. “Iran has shown everyone that when it is pressed hard it knows how to stop and change its ways.”

The Jerusalem Declaration further committed the United States and Israel to cooperating on defence projects such a laser interceptors, as well as on civilian technologies.

The United States was open to future defence grants to Israel, the statement said, reaffirming Washington’s interest in reviving talks on an Israeli-Palestinian two-state solution.

(Writing by Dan Williams; Additional reporting by Jarrett Renshaw and Arshad Mohammed; Editing by Howard Goller, Nick Macfie, William Maclean)