An exhibit opening this month at the US Holocaust Museum in Washington asks the question: What did Americans know in real time about the Nazi slaughter of Jews in Europe? It turns out that ordinary Americans, and certainly government decision-makers, knew a lot about Nazis and the Holocaust as it was happening – and quite early in the war.But this was based on partial information; there was no absolute proof; and nobody wanted to be branded an alarmist.Moreover, few wanted to pay the price of moral action.Turning a blind eye was somewhat easy because there were no YouTube videos or satellite feeds, no Facebook, WhatsApp or Twitter messages with pleas for help from about-to-be-gassed- and-incinerated Jews.So people preferred to pretend they didn’t know, or could tell themselves that they weren’t sure enough to act, or could accept denials of the emerging atrocities at face value.You might say: There was no smoking gun.In today’s world, none of these exculpations hold water. In today’s world – with live news and social media feeds everywhere – everybody knows everything instantaneously. It’s hard to take refuge in denial when atrocities occur or when threats are building up.And yet, in relation to the Mideast, people have preferred to pretend they didn’t know, or to tell themselves that they weren’t sure enough to act, or to accept denials of the atrocities and threats at face value.This applies to the seven-yearlong war in Syria and to massive human-rights violations in Turkey.The community of democracies has done nothing to stop Assad’s slaughter and few have protested Erdogan’s dictatorial takeover.This also applies to the Hezbollah missile buildup in Lebanon, to Yasser Arafat’s and Mahmoud Abbas’s antisemitic leadership of the Palestinian national movement, and so much more. People have preferred to look the other way or to pretend they didn’t fully know – and thus they are not compelled to act.The same goes for the Iranian drive to build nuclear weapons.Up until now, the argument could be made – barely – that the evidence for Iran’s two-decades- long drive for a working nuclear bomb was based on partial information. Nobody really knew for sure, there was no absolute proof. And in this situation, nobody wanted to be branded an alarmist or pay the price of moral action needed to truly stop Iran.It was more comfortable to accept Iran’s denials and Iranian Foreign Minister Zarif’s smiles. And thus, then-president Barack H. Obama could impute credibility and honesty to the Iranian leadership. As justification for his softball approach to Tehran, Obama referred in 2013 to a supposed fatwa by the Iranian “supreme leader” against the development of nuclear weapons and to President Rouhani’s “promise that Iran will never develop a nuclear weapon.”See-no-evil secretary of state John Kerry similarly testified to Congress in 2015 that he believed the “sincerity of the supreme leader.” (Kerry could see no evil in Iran, only in Israeli settlements.) CONSEQUENTLY, THESE American leaders forgave Iran on the demand that it come clean on the “possible military dimensions” (PMD) of its previous nuclear program, and decided to forgo the demand that Iran categorically allow anytime-anywhere inspections of its military nuclear installations.So now that Israel has provided a smoking gun that proves the definite military dimensions pursued by Tehran – original official documents retrieved from an atomic archive with the stamp of the Iranian regime – the question is: Will the dissimulators and disbelievers repent? Will they admit that they were wrong about Iran’s intentions? That they willingly allowed themselves to be duped by Tehran? That the Iranian regime never took nuclear weapons option off the table? Because if they knew everything the Iranians were up to – as Kerry and the European Union’s Frederica Mogherini and some French and German leaders are now retroactively claiming – the weakness of the nuclear deal (the Joint Comprehensive Plan of Action) is even more indefensible! Alas, repentance by American and European boosters of the JCPOA doesn’t seem to be in the cards. Instead, they sneered this week at Israel’s intelligence coup, pointing to Prime Minister Benjamin Netanyahu’s ostensible failure to produce evidence of current Iranian accord violations. “Israel produced nothing new,” they guffawed.This is both untrue and beside the point.It’s untrue, because there are apparently massive amounts of new information in the treasure trove secured by Israel about the details and scope of the Iranian nuclear effort; the people involved in it (and who probably still are); locations of hidden nuclear development sites; front organizations Iran set up to pursue nuclear parts and knowhow within the framework of the deal; records of Westerners who collaborated in smuggling components for the nuclear effort; and so much more.It is also beside the point. Israel’s central contention all along has been that the JCPOA is so badly constructed that the Iranians have no reason to violate it today.Under the terms of the accord, Iran can continue to develop centrifuges for enrichment and ballistic missiles for delivery of nuclear weapons and just wait a few years before all sanctions are lifted and limits on uranium enrichment expire.In short, the JCPOA was based on Western charity for Iranian lies (as well as additional misrepresentations like the “need to strengthen moderates in Iran” that the P5+1 peddled to overcome opposition to the accord). It relied upon Western predilections to look away and pretend that one didn’t really know. After all, there was no smoking gun.Until now.After Israel’s intelligence coup, the question becomes this: Will JCPOA boosters continue to deny reality and accuse Israel of being alarmist? Will they continue to pretend they didn’t know, and to accept Iran’s naked denials? Can they possibly continue to defend the weak verification procedures and early sunsets of this inadequate accord? Let’s hope that US President Donald Trump calls the global bluff and reinstates crippling sanctions on Tehran alongside a credible threat to use military force. It’s time to ensure that Iran genuinely rips to shreds every aspect of its nuclear program, in perpetuity.The writer is vice president of the Jerusalem Institute for Strategic Studies, jiss.org.il. His personal site is davidmweinberg.com.