Sima Shine, former head of the Mossad’s research and evaluation division, and Elliott Abrams, former foreign policy adviser to three Republican U.S. presidents, agree that the military option against Iran is a last resort.

As U.S. National Security Advisor Jake Sullivan arrived in Israel on Tuesday to discuss Iran and other strategic issues, and as nuclear talks continue in Vienna – albeit at a snail’s pace – the Israeli leadership increasingly believes that applying heavy pressure on Tehran is the only way to stop the Iranian advance toward nuclear weapons.

But where exactly do the U.S. and Israel go from here on the Iranian threat?

Sima Shine — head of the Iran program at the Institute for National Security Studies (INSS) think tank as well as former head of the research and evaluation division at the Mossad — explained during a virtual event last week that Israel is faced with three main issues today with regard to Iran.

The first and most prominent is the nuclear program. The second is the fact that Iran is close to Israel’s borders in Lebanon, Syria and Gaza. The third involves cyberattacks carried out by Iran against Israeli infrastructure and civilian entities.

“The nuclear threat is the only strategic – some would say existential – threat that Israel faces,” Shine said. “Bottom line, Iran is closer to the decision if they decide to enrich to military grade.”

“The closer Iran gets to a nuclear weapon, the more temptation there is to get there,” she added.

Addressing the ongoing discussions in Vienna, Shine said that all available scenarios for Israel are unappealing.

“The less bad [scenario] would be if Iran rolls back its program to give Israel and the U.S. more time to prepare for the future,” she said. “In Iran there is no appetite for going back. The worst would be if the talks fail and Iran heads towards further enrichment.”

In the virtual conversation – part of a larger series cosponsored by Tikvah Israel in Jerusalem and the INSS in Tel Aviv – Tikvah Fund Chairman and former foreign policy adviser to three Republican U.S. presidents, Elliott Abrams, said there is “broad consensus that the main challenge of the 21st century is China. The Middle East is a diversion.”

“America wants stability in the Middle East, so that it can shift its focus to China and Asia,” said Abrams, former U.S. Secretary of State Mike Pompeo’s special representative for Iran and Venezuela, and currently a senior fellow at the Council on Foreign Relations.

“The greatest threat to stability would be Iran’s acquisition of a nuclear weapon because it could lead to a nuclear arms race in the region.”

“We see the behavior of Iran in Syria, Lebanon, Gaza and Yemen,” he said. “All of this is undertaken without nuclear weapons. One therefore must ask oneself: What would Iranian behavior be like if it felt safer because it had a nuclear weapon?”

Abrams said Iran’s effort to acquire a nuclear weapon could plausibly lead to a military confrontation with the U.S. or Israel.

Noting that U.S. President Joe Biden has said Iran will not obtain a nuclear weapon, Abrams said it is “therefore destabilizing and terribly undermining of U.S. leadership and credibility if all of these pledges and promises by American presidents over the years turn out to be hollow, and it turns out they can be defied by Iran with no impact or reaction on the part of the United States.”

The reason this is so dangerous, he explained, “is because the credibility of the United States is pledged in other places such as NATO or Taiwan. Such a devaluation of American credibility would be a big change in international politics.”

Abrams emphasized that the world order “is largely based on the credibility of the U.S. And if that credibility disappears, we have a whole different world.”

“Today, that credibility is less solid than it was 10 or 20 years ago,” he said.

“An Iranian nuclear weapon, in the teeth of the American pledge ‘this will never be permitted to happen,’ would really do SERIOUS damage to America’s interests throughout the world.”

According to Abrams, the only way to avoid the two polar results – an Iranian nuclear weapon or a military strike of some kind against Iran – is to put enough pressure on Iran so that it will negotiate. “And that must include sanctions and a credible military threat,” he said. “And I’m not sure Iran believes today that it faces a credible military threat.”

Abrams said that in the absence of a strong nuclear agreement, the U.S. “should go back to the most intense economic pressure on Iran and on making it clear that military action is possible and is preferred to the Iranian possession of a usable nuclear weapon.”

He also agreed with Shine that the closer it gets to achieving a nuclear weapon, Iran will not want to remain a threshold state.

“I have never lost sleep because Japan is a nuclear threshold power,” he said, explaining that with Iran, “The problem is not the technology, it’s the regime, which is aggressive and hostile. And the degree of its hostility to Israel and the United States is extraordinary, from the first day in power in 1979 to today.”

Shine said she does not favor any military confrontation “because both sides will pay heavily.” That said, she admitted that the military option is “a last resort and only in a severe situation. I do hope if we get to that point, it will be a coalition and Israel will not be alone at the head of such a strike. It is not only an Israeli problem. It is a U.S. and European problem.”

Abrams pointed to history to demonstrate what could be learned from previous attempts to neutralize nuclear sites.

“Iraq and Syria bring the lesson that they did not lead to war,” he said, referring to Israel’s successful strikes against those countries’ nuclear reactors in 1980 and 2007, respectively.

Like Shine, Abrams said the use of force against Iran would be a last resort.

“This is a different case than Syria or Iraq with many more global repercussions,” he said. “If force must be used, I would favor the U.S. doing it. I would never argue that Israel should take this exclusively upon itself.”

In conclusion, Shine said Israel has shown previously that when it comes to the crucial issue of security, the Jewish state takes the decisions needed to ensure its national security.

“I do hope the U.S. coalition, with the support of like-minded countries as well as China and Russia which do not want to see a war in the Middle East, will put enough pressure on Iran to make sure they do not continue with their violations and roll them back,” she said.

Abrams said the “best outcome here is stopping Iran without the use of force. That is still conceivable but only if two things happen: more economic pressure and an absolutely credible military threat.”