The Post reports:

The Obama administration said Thursday that Iran is helping al-Qaeda funnel cash and recruits into Pakistan for its international operations, the most serious U.S. allegation to date of Iranian aid to the terrorist group.

Documents filed by the Treasury Department accuse Iran of facilitating an al-Qaeda-run support network that transfers large amounts of cash from Middle East donors to al-Qaeda’s top leadership in Pakistan’s tribal region.

Most readers and Americans would have no idea that a huge controversy raged between liberal and conservative policymakers, analysts and lawmakers over whether such a connection existed. Sens. Joe Lieberman (I-Conn.), Jon Kyl (R-Ariz.) and Mark Kirk (R-Ill.) today issued a joint statement regarding the U.S. Treasury Department’s designations of six al-Qaeda facilitators, including two based in Iran that alluded to the controversy: “For many years, some have insisted that religious divisions would prevent Shiite Iran and Sunni al-Qa’ida from working together against us, but that ignored the fact that both want to destroy us. The fact that the Iranian regime has a secret ‘agreement’ with the terrorist group that is responsible for the 9/11 attacks and that continues to try to strike Americans at home and in the region reinforces why Iran is such a uniquely dangerous threat to our country and to the world.”

Iran expert and former CIA case officer Reuel Marc Gerecht of the Foundation for Defense of Democracies was part of that debate. He e-mails me:

Iranian-al-Qaeda ties were perhaps the most interesting and dangerous part of the 9/11 Commission Report. It is shocking to recall the counterterrorist experts of the Clinton and Obama administrations — let alone President Obama and Vice President Biden, who used to refer to al-Qaeda holy warriors in Iran as being “under arrest” — who have assiduously turned a blind eye to this deeply disturbing information about Iranian complicity in al-Qaida terrorism. My Lord, Ayman az-Zawahiri, now the leader of Al-Qaeda, was Iran’s favorite Sunni jihadist poster boy, an honored guest in Iran in the 1980s. If Al-Qaeda again gains a global strike capacity, it will most likely be because of the aid that Ali Khamenei, Iran’s supreme leader, and his Revolutionary Guard Corps have given it.

Gerecht explains that this has policy ramifications as well: “It is just nuts that so many on the left and the right have looked upon this regime’s quest for nuclear weapons as a threat best handled by diplomacy and at most sanctions. This is not a status quo regime. It conceives of itself as an Islamic revolutionary vanguard. It has always been ecumenical in its attitudes towards Sunni jihadists. You should no more allow this regime nukes as you would allow the bomb to az-Zawahiri.” The three senators echoed this sentiment in their statement: “This revelation should also inject renewed impetus to our efforts to stop Teheran’s accelerating nuclear drive. Any regime that makes secret deals with al-Qa’ida cannot be allowed under any circumstances to possess a nuclear weapons capability.”

Gerecht colleague Jonathan Schanzer recalls: “This is not a surprise. The 9/11 Report called upon the intelligence community to explain the intelligence it found linking al-Qaeda to Iran. Nothing came of it. Treasury has also designated other al-Qaeda targets in the past. Nobody seemed to notice. And of course, al-Qaeda enjoyed safe haven in Sudan during the early 1990s when that country was under the strong influence of the mullahs. Did anyone really think that ties weren’t forged?’”

In other words, this is only a surprise for some people. He explains, “In short, this new tranche of Treasury designations is illuminating (and may be the direct result of the raid on bin Laden’s compound in May), but the writing has been on the wall for years.”

As The Post notes: “Although U.S. officials have repeatedly accused Iran of assisting al-Qaeda, links between the two have been difficult to prove. Al-Qaeda regards the Shiite denomination, the dominant branch of Islam in Iran, as heretical, and Iran has sought at times to crack down on the terrorist group, deporting some operatives and holding others under.” But it turns out the ideological divide was irrelevant, just as conservatives had argued.

The Wall Street Journal editorial board provides some needed perspective:

That there have long been links between al Qaeda and the government of Iran isn’t exactly news.

In 2003, the Washington Post reported on a “decade-old relationship” between al Qaeda’s Ayman al-Zawahiri and Ahmad Vahidi, now Iran’s minister of defense. In 2004, the 9/11 Commission wrote that “there is strong evidence that Iran facilitated the transit of al Qaeda members into and out of Afghanistan before 9/11, and that some of these were future 9/11 hijackers.” Throughout the war in Iraq, there was extensive intelligence that Iran was supporting the Mesopotamian branch of al Qaeda, never mind that they were terrorizing the country’s Shiite population.

Yet it was only yesterday that the U.S. government formally acknowledged the connection between the world’s most dangerous terrorist group and the leading state sponsor of terrorism. . . .

The sanctions will likely have little effect on the terror network, at least so long as its members remain in the Islamic Republic. But at least it ought to put to rest the idea that doctrinal differences all but forbid radical Sunnis to make common cause with radical Shiites. As in politics, terrorism can make strange bedfellows, especially when there’s a shared hatred of the United States. . . . . Above all, it’s a reminder of why a regime that has no qualms serving as al Qaeda’s facilitator can on no account be permitted to build a nuclear bomb.

So actually it wasn't difficult to prove the Iran-alQaeda connection, it was just hard to admit it. Presumably the left will shrug its collective shoulders as this finding now slips into conventional wisdom, with nary a trace that so many for so long believed something so wrong.