Based on interviews with key Bush administration officials that were conducted by PBS Frontline in 2007, skepticism abounded over the document’s backchannel transmission and its discordancy with the kind of Iranian behavior—such as growing support for anti-American proxies in Iraq—that the White House was seeing at that time. Therefore, senior officials disagreed on the right course of action: Secretary of State Colin Powell, Deputy Secretary of State Richard Armitage, and Senior Director for Middle East Affairs at the NSC Flynt Leverett cautiously favored engagement, but Vice President Dick Cheney, Secretary of Defense Donald Rumsfeld, and UN Ambassador John Bolton rejected negotiations—and the letter—out of hand. With the bombing in Saudi Arabia occurring soon after, the administration’s hawks felt further emboldened. President Bush not only rebuffed the overture and gave no response, but also halted the dialogue with Iran over Afghanistan and Iraq. Although the letter’s veracity continues to be debated today, Iran expert Vali Nasr has offered a discerning assessment:

We forget that this offer came after Iran made its boldest cooperation with the United States over Afghanistan, only to be put on the “axis of evil” list afterwards … So as the [Mohammad] Khatami government, the reformist government, is making one last effort to make a pitch to the U.S., it is running a risk. And I assume that their hope was that the U.S. would test the proposal by coming back, which then would have made a signal to the Iranian leadership that the U.S. was interested, and then you could see whether the Iranians would come back with something more concrete. The Iranians were testing, and the test came back negative.

AFTER THE Bush administration aborted negotiations, Washington and Tehran would not attempt to reopen bilateral discussions on Iraq until 2006. The past three years had seen Iraq slide into anarchy: De-Baathification had deeply aggravated resentment within the Sunni community, which—despite being a minority—had become accustomed to wielding disproportionate political power under Saddam Hussein. Unemployed and now living under a Shia-dominated political system, some Sunnis embraced violence as Shia militias, bankrolled by Iran, and disaffected former Baathists, aided by Syria, also took up arms. Al Qaeda in Iraq (AQI) terrorists only made matters worse by carrying out vicious sectarian killings; a resilient insurgency had taken root.

Appointed U.S. ambassador in 2005, Khalilzad moved aggressively to stabilize Iraq. His writings in The Envoy specify how, as he engaged all sides of Iraq’s broken polity, he deduced that attaining political reconciliation and reducing violence would be easier with Iranian buy-in, since Tehran had a financial “stranglehold” on Iraq’s Shia Arabs, influence with the Kurds, and was callously exploiting violence to manipulate Iraq and bog down U.S. forces. Outgunned and politically constrained in this financial contest, Khalilzad appealed to President Bush to confront Iran over militia attacks on U.S. forces, the Quds Force’s political assassinations and its distribution of explosively formed projectiles—a deadly roadside bomb that would eventually kill and maim hundreds of U.S. troops—and Tehran’s tolerance of AQI members transiting its territory. His pleas failed; the White House was wary of expanding the conflict.

By 2006, the Bush administration’s Iran policy was contradictory and troubled. The White House persistently refused direct negotiations with Iran without preconditions even as U.S. diplomats were crafting an incentive package alongside the Europeans, Russians, and Chinese to curtail Iran’s uranium enrichment program. However, after some debate, Bush authorized Khalilzad to open discussions with Iran, and senior Iraqi politician Abdul Aziz al-Hakim traveled to Tehran with a U.S. olive branch. Hakim returned with good news: Iran was interested in engaging, and Khamenei had “put together a team from across the Iranian foreign and security departments” to talk about “all the issues dividing the United States and Iran.” Yet, in a regrettable about-face, the Bush administration abruptly pulled Khalilzad from the talks.

America and Iran would not officially speak again until the following year, when Bush reversed course again and directed Crocker, then U.S. ambassador to Iraq, to attend “circumscribed” talks with Hassan Kazemi Qumi, a veteran Quds Force officer who was Iran’s ambassador to Baghdad. Crocker would tell The New York Times in May 2007 that there was “good congruence” between the two nations on the contours of a future free Iraq, but that they disagreed on how Iran’s support for Iraqi militias was affecting internal violence. The militias’ role in attacking U.S. troops would become a sticking point, leading Crocker to complain that Iran’s offer to establish a “trilateral mechanism” for “militias, Al Qaeda and border security” was stalled and violence was escalating. The meetings buckled in August, in part due to, a senior Iraqi intelligence official later told U.S. Army general David Petraeus, America dealing with the wrong interlocutor—only Iran’s viceroy for Iraq, Qassim Suleimani, could reduce the violence. Thus, Iran’s reported desire for these discussions to be a launchpad for “higher-level talks” went nowhere. The United States was evidently unwilling to accept that, for its Middle East security objectives to succeed, it must deal directly with Suleimani and the IRGC Quds Force.

WHILE IT’S debatable whether U.S.-Iran negotiations failed because the Bush administration was, as Khalilzad asserts, unwilling to combine “diplomatic engagement with forcible actions” to “take on Iranian activities in Iraq,” it is clear that the region—and the United States—would have benefitted from their success. Indeed, when Barack Obama was elected U.S. president, he hoped that his own brand of “aggressive personal diplomacy,” he told The New York Times, could produce dividends. The eventual success of Obama’s sanctions diplomacy, which culminated in the JCPOA, is often contrasted with his missteps on Iraq, where his most infamous decision, the 2011 withdrawal of U.S. troops, is still blamed for producing the Islamic State of Iraq and Syria (ISIS). In the words of James F. Jeffrey, a career diplomat currently serving as President Trump’s special envoy to Syria, that criticism is “hogwash,” but the U.S. military’s departure did leave Iraq increasingly vulnerable to a still-festering political-security fracas that Washington had created in 2003. Neither the Americans nor Iraqis had been able to fill this power vacuum, but the Iranians—and Al Qaeda—were keen to exploit it. This struggle for power in Baghdad exposed Iraqis’ deep-rooted but previously dormant sectarian tensions and laid the groundwork for AQI terrorists to transmogrify into ISIS. No realistic amount of U.S. troops or occupation timetable could have stitched Iraqi society back together, but U.S.—and Iranian—troops would be critical to destroying this global terrorist menace.

Since Iranian influence and military assets were pervasive in both Iraq and Syria, the United States knew that Iran could be a pivotal force against ISIS. However, the JCPOA’s adoption had already perturbed many U.S. Middle East allies, and the Obama administration was loath to alienate them further by offering unprecedented military assistance to Tehran. This context helps explain the events surrounding President Obama’s missive to Iranian supreme leader Khamenei in October 2014, when the U.S. president made a contingent proposal for cooperation against ISIS if the two nations could first reach a nuclear deal. When the letter was later uncovered by The Wall Street Journal, Obama denied this linkage in a November 9 interview with CBS’ Face the Nation and further clarified that he only wanted deconfliction with Iran, rather than “coordination or [a] common battle plan” against “our shared enemy.” ISIS took a backseat to nuclear diplomacy; it was not the priority.

Fraught domestic politics made—and continue to make—extraordinary overtures to Iran difficult, and much of America’s diplomatic bandwidth was then focused on finalizing the JCPOA. However, geopolitics was also driving U.S. and Iranian ISIS policies in Syria and Iraq, and there was only modest agreement in between them. For example, even as the Obama administration told Iran it was uninterested in forcibly ousting Syrian president Bashar al-Assad, leaked remarks made by former U.S. secretary of state John Kerry in 2016 clarify that the United States had been “watching” ISIS’ Syrian rise and intended to “manage” it to compel Assad to negotiate a political transition. Thus, despite Kerry speaking with Iranian foreign minister Zarif about ISIS on the sidelines of the nuclear negotiations in 2014, and the Obama administration’s 2015 National Security Strategy citing the “persistent threat” of both ISIS and Al Qaeda before either Russia or China were even mentioned, the White House did not adjust its regional policies in any dramatic fashion to prioritize that threat. Rather than endeavor to use the anti-ISIS fight as an opportunity to jumpstart regional cooperation against extremism—as Russia did by arranging a joint intelligence-sharing agreement with Iraq, Iran, and Syria in 2015—Washington and Tehran fiercely competed in Syria and quietly used one another in Iraq.

After ISIS emerged, Washington and Tehran’s mutual hatred of ISIS fostered the conditions for a de facto collaborative military campaign throughout Iraq, despite that both Iran and America preferred to go it alone. For instance, as Baghdad began to rely on militias for its security after the collapse of the Iraqi Army in 2014, Washington had to recognize that the Shia-majority Popular Mobilization Forces (PMF), the umbrella name for Iraq’s militia network, was the most decisive anti-ISIS force in Iraq—in no small part due to extensive Iranian support. The U.S. military strived to fight ISIS without directly aiding these forces—as demonstrated by the Pentagon’s demand that Iranian-aligned militias withdraw from Tikrit before U.S. warplanes would assist the Iraqi government’s assault—but U.S. arms routinely found their way to into their hands, and different PMF factions regularly benefitted from U.S. air support.