By Aaron Kliegman When Joe Biden was vice president, the US had an obsession: establishing friendlier relations with Iran through diplomacy — specifically, a nuclear deal. This obsession dominated the Obama administration’s approach to the Middle East, superseding all other concerns. Biden may try to revive this agenda as president, but he’d be wrong for doing so — as a recent assassination makes clear. Over the weekend, the New York Times reported that, “at the behest” of the US, Israeli operatives killed al Qaeda’s second-highest leader, Abu Muhammad al-Masri, in Iran on Aug. 7. According to the article, two assassins on a motorcycle fatally shot al-Masri as he was driving in the streets of Tehran, the Iranian capital. Other media outlets later confirmed the report, noting that Israel and America worked together to track and kill al Qaeda’s No. 2. Reportedly, al-Masri was planning attacks on Jewish and Israeli targets around the world at the time of his death. The most important detail of this story is its location. According to conventional wisdom, al Qaeda’s second in command shouldn’t have been in Iran. “Iran, a Shiite Muslim theocracy, and al Qaeda, a Sunni Muslim jihadist group, have fought each other on the battlefields of Iraq and other places,” reported the Times, which described Iran and al Qaeda as “bitter enemies.” Many analysts and politicians, especially those on the political left and the isolationist-leaning right, assert that Iran and al Qaeda have never cooperated in any significant way. How could they? After all, they’re ideological rivals. And yet, al-Masri was living freely in an upscale suburb of Tehran. It turns out that Iran and al Qaeda are perfectly willing to cooperate against their common enemies: America and Israel. Of course, both sides have openly fought each other in places such as Syria and Yemen. But nonetheless, Iran and al Qaeda formed a complicated alliance that dates back to the early 1990s, when both sides began a decades-long collaboration that continues today. The evidence is ample — and irrefutable. According to the 9/11 Commission Report, for example, Iran and its chief proxy, Hezbollah, gave al Qaeda the “tactical expertise” it needed to carry out the devastating 1998 attacks on US embassies in Africa — attacks that al-Masri helped plan and that landed him on the FBI’s Most Wanted Terrorist list. The partnership evolved from there, especially after 9/11 and the fall of the Taliban in Afghanistan. Senior leaders of al Qaeda fled to Iran, where they ultimately reached an agreement with the Iranian regime. The Treasury Department described this arrangement well in 2012. “Under the terms of the agreement between al Qaeda and Iran,” the department reported, “al Qaeda must refrain from conducting any operations within Iranian territory and recruiting operatives inside Iran while keeping Iranian authorities informed of their activities.” In return, Treasury continued, “the government of Iran gave the Iran-based al Qaeda network freedom of operation and uninhibited ability to travel for extremists and their families.” Documents recovered at Osama bin Laden’s compound in Pakistan affirmed this deal, detailing how Iranian intelligence provided safe haven to members of al Qaeda, facilitated travel of some operatives, and even offered money, arms, and training to the terrorist group. Al Qaeda benefited immensely from Iran’s support. Just read a letter from October 2007 to an unknown jihadist called “Karim.” The letter, which analysts believe was most likely written by bin Laden, explains that Iran was al Qaeda’s “main artery for funds, personnel, and communication, as well as the matter of hostages.” All of this begs obvious questions. Why should the US try to establish friendlier relations with a regime that supports those responsible for 9/11? Why should we consider lifting sanctions on a country whose government helped al Qaeda rebuild itself? Why should we be OK with such a murderous, anti-American theocracy building a nuclear infrastructure? These are good questions to ask Biden, who wants to return to the nuclear deal with Iran. To paraphrase former Secretaries of State George Shultz and Henry Kissinger, the nuclear deal concedes the capability that it was supposed to prevent: Iran’s ability to develop a nuclear arsenal. All the deal does is delay this nightmare for about a decade — while giving Iran billions of dollars by lifting sanctions in the meantime. Perhaps Biden would demand as part of a renegotiation that Iran cut all ties to al Qaeda. All evidence, however, points to him making endless concessions in hopes of reviving the deal. A Biden administration would be staffed largely by alumni of the Obama administration, which saw the nuclear deal as the vehicle to begin moderating the Iranian regime and creating a new equilibrium in the Middle East under which Iran and America’s allies “share” the region. Iran’s leaders are well aware of this fact, which is in part why they’re continuing to violate the nuclear deal egregiously. They clearly think they can pressure a Biden administration to negotiate a new deal favorable for Iran, believing Biden and his team would do everything possible to avert a crisis and possible conflict. The leaders of Iran are probably right. They’re not stupid, just evil — evil enough to support those responsible for 9/11. Indeed, calling Iran the world’s foremost sponsor of terrorism isn’t a talking point; it’s the truth.