One approach for limiting Iran’s further nuclear expansion that the United States has yet to consider, but needs to start, is setting some clear red lines that, if crossed, would trigger a far more punishing response against Iranian interests. Last June, at an earlier stage of the brewing crisis, I suggested that those lines might be drawn at Iran starting to enrich again to 20 percent or significantly curtailing IAEA inspections. Obviously, no such messages were delivered and seven months later, Iran has blown through each of those thresholds with impunity.

Of course, there’s no way to prove that Iran wouldn’t have done so even if the red lines had been established. But as I noted in my article, there is strong precedent for suspecting that the regime might take such limits quite seriously. Though heavily derided at the time, in a 2012 speech at the United Nations, Israeli Prime Minister Benjamin Netanyahu literally drew a red line on a cartoon bomb and left no doubt that if Iran accumulated a stockpile of 20 percent uranium sufficient for one nuclear bomb, Israel would act against the Iranian program. What few people remember is that the Iranians thereupon scrupulously ensured that their stockpile remained under the threshold needed for a bomb’s worth of material. It was almost certainly an instance of successful deterrence that deserves far greater study by U.S. policymakers than it has received.

The risks associated with red lines, as with most deterrent threats, are well known. In the first instance, if crossed, they need to be enforced, requiring the United States to undertake difficult actions, often involving the use of force that no president is eager to commit to in advance. If not enforced, and exposed as nothing but an empty bluff, the impact on American credibility with adversaries far and wide could be damaging. For evidence, just see President Barack Obama’s red line regarding the Syrian regime’s use of chemical weapons in 2013. There’s also the dilemma that once a red line is communicated, it could be interpreted as giving an adversary license to engage in all sorts of dangerous provocations just short of the threshold.

All these factors and others would need to be carefully assessed by the Biden administration and weighed against the rising risk of Iran continuing on its present trajectory of pressing its program forward without any sense of outside constraints whatsoever—short of actually dashing to build a nuclear weapon.

Ideally, a red line strategy would be pursued with key allies in Europe and Israel. As JCPOA participants in good standing, the EU-3 wield the potentially powerful card of unilaterally invoking the deal’s snapback provisions, which would return the full weight of UN resolutions, sanctions, and diplomatic isolation crashing down on the Iranian regime’s head. With Europe’s bete noire, Donald Trump, now gone, and with a Biden team working in tandem with London, Paris, and Berlin to restore the JCPOA, the EU-3 might well be willing to finally unsheathe their snapback sword in the interest of a targeted red line strategy meant to deter the next major leaps forward in Iran’s nuclear advancement—whether that be accumulating a bomb’s worth of 20 percent uranium, moving to 60 percent enrichment, destroying critical information gathered through remote IAEA monitoring systems, or the industrial production of uranium metal. It’s certainly a conversation that the administration should urgently be exploring with the EU-3, and would put some much-needed teeth behind an existing approach that is currently in danger of devolving into little more than endless hand-wringing over the danger of each new Iranian violation, pleading with the regime to return to JCPOA compliance, and offering a growing list of concessions and payoffs—euphemized as confidence-building measures—to entice Iran back.

Israel, of course, is the only other country along with the United States that can put forward a credible kinetic component, whether overt or covert, as part of a red line strategy. Indeed, in light of Israel’s stunning record of success in conducting direct action operations against Iran’s nuclear program, the Iranians may well take an Israeli red line more seriously than one coming from the United States alone. Far better, of course, if it were to come from both. The Biden administration has convened a new strategic dialogue with Israel to try and develop a common approach, especially with respect to the administration’s strategy on reviving the JCPOA. Those discussions have begun none too soon and the pros and cons of a possible red line strategy and how it could most effectively be implemented should be a central focus.

Biden and his advisors seem all-in on an effort to get Iran back into compliance with the JCPOA. But as they work to do so, they readily acknowledge that, day by day, Iran’s nuclear advancements are becoming more and more dangerous. The Trump administration, to its great discredit, never developed a serious answer to this growing threat when its plan A—forcing Iran to scale back its nuclear escalation through maximum economic pressure—failed to deliver. The question now is whether the Biden administration can do better. Can it develop a diplomatic strategy for constraining Iran’s accelerating nuclear clock even as it seeks to revive negotiations—one that doesn’t just involve outright capitulation to Iran’s demands and the surrender of all U.S. negotiating leverage and credibility? If the administration is serious about the challenge, the issue of red lines should urgently rise to the top of its agenda. 

John Hannah served in three U.S. administrations, including as national security advisor to former Vice President Dick Cheney. He is an advisor to the JINSA Gemunder Center for Defense and Strategy.

Image: Reuters.