So much of U.S. policy in South and West Asia has been determined by Washington’s relationship with two countries: Iran and Pakistan. But the relationship between these two regional powers has been in many ways as influential as their swings from allies to frenemies to adversaries with the United States. The ties between Iran and Pakistan run deep, and they have shifted over time from a deep affinity to regional rivalry and proxy conflict. Underneath it all has been the two countries’ pragmatic self-interest. “Neither country has ever genuinely considered optimum relations as an end in itself,” Alex Vatanka writes in the introduction to his book, "Iran and Pakistan: Security, Diplomacy and American Influence." “For both Iran and Pakistan, bilateral closeness was always meant to reap something strategically larger.” But over the past seven decades, since Pakistan’s inception, their relationship has been buffeted by global and regional competition, by the Cold War, the scramble for Afghanistan and the Iran-Saudi rivalry.

I recently finished reading Vatanka’s book and had the opportunity to discuss the history of the Iran-Pakistan relationship with him by phone. “In this relationship, for the United States watching is not an option,” he told me. “This is a relationship involving two large countries, one is already nuclear-armed, one is a threshold nuclear-armed state, combined something like 300 million people, almost the size of the U.S. population. It's a big market potentially if we wanted to integrate them. There are a whole host of areas where we can cooperate in terms of counterterrorism, trying to bring some sort of stability to Afghanistan. If you let the diplomats, perhaps, and economic entry have a bigger say and not look at the relationship purely through the security prism, which is where we are now, then this relationship can improve and become more healthy than it is today. It's clearly unhealthy today.” Our conversation has been edited for length and clarity.

Could you start by explaining why you wanted to focus on Iran and Pakistan?

Almost for the last 20 years, I've been covering Iranian affairs—domestic, foreign, and a lot of regional dynamics involving Iran and its neighbors. When you look at Iran's immediate neighborhood, including its 15 immediate neighbors (if you include its land and maritime neighbors), there’s plenty of literature on most of the neighbors' relations with Iran. Certainly among those neighbors, we'd consider them the big neighbors, Saudi, Turkey, Iraq, Afghanistan—Pakistan stands out as one that hasn't really been tackled in the context of its relations with Iran. So I thought, 'Here's a gap, here's a deficiency, and why not try to see if we can find out more about it?' That was really the beginning of that research idea, project and the subsequent book that came out of it.

I think the history alone is really interesting, and there's a lot of that in the book, but I think there's a lot more to it than just the historical narrative. I think if you look at these two large countries, as they sit in Asia, anyone who wants to figure out how the large-power politics, the race for influence in this part of the world happened, needs to take into account what drives Iran and Pakistan and where they come from in term of their past, where they are today, and where they are likely to go forward.

But this book is not just about history. The book is trying to say, This is the history, these are the complications, these are the moments they were together or where they parted ways. But just as the United States is trying to figure out, the question is: What are we going to do with West Asia? We have so much in terms of interests—not just preserving or even reaping the fruits of 16 years of American involvement in Afghanistan. How do we do that? How do we address those national security interests? Will we know what the Iranians and Pakistanis are up to? Now, the U.S. has different relations, obviously, with Iran and Pakistan, they're very different, and they're both challenges—different sets of challenges. What I was trying to do with this book is to show through a historical lens the path they traveled to get to the point where they are today, both in their bilateral relations and in how they look at the region—different as it is, but their interests in the region—and what that means for the United States.

One of the things that come through clearly in the book is how complicated that relationship is. Both countries have considered themselves regional powers, and there's the constant competition for primacy in South and West Asia, but they also used to have much more cordial ties than they do now. You even write about how Pakistan looked to Iranian laws as some of the potential foundation for their model, and at times they even flirted with the idea of unification. What was the foundation of that cordial relationship, and what changed to put them in the place where they are now?

Well, before I answer the question, let me just take one step back and tell you, from my perspective, when we talk about "complicated relations," what we really mean is obscure to observers outside. Why's it so obscure? The reason for that is, unfortunately, so much of the relationship has been shaped and driven by the respective intelligence and military agencies of the two countries. Iranian and Pakistani diplomats are not in the forefront of shaping Iranian-Pakistani relations. By the nature of intelligence organizations and military organizations in this part of the world, there won't be much information coming out. This creates a layer of uncertainty about what motivates them. It forces all of us really engaged in it to get thinking, Why are things happening the way they are? Because so much of it is in that darker realm of intelligence warfare and competition between the two countries.

[S]o much of the relationship has been shaped and driven by the respective intelligence and military agencies of the two countries. Iranian and Pakistani diplomats are not in the forefront of shaping Iranian-Pakistani relations.

Now, that said, let me go back to the question about why we're where we are today. When Pakistan is created following the Second World War and the British pull out of the so-called British Raj, they are sitting here in this Muslim-majority part of India with large [inaudible] in the east. They quickly become the eternal enemy, and that's where we are today so many decades later. By geography, by historical connections of the past, Pakistan very quickly turns to their west, where they find a country in Iran that is Muslim, like the Pakistanis are; that is anti-Soviet, like they are; and that also has at the time, in the 1940s, a relatively young king in the shape of Mohammad Pahlavi, who was the shah, who is looking to find his way around this extremely fluid post-world-war configuration in the Middle East. There are these common interests, and obviously the United States is encouraging Iran and Pakistan to work closely. This is the beginning. It's very important, as we look forward to what happens decades later, they begin as a relationship that's convenient because both countries have larger enemies or interests outside the confines of the bilateral relationship.

Iran had always been really useful as long as it was able to help the Pakistanis against the bigger threat of India. Once Iran becomes almost a pariah state, then the fact that there's geographical proximity, or that there's all sorts of other similarities between them—they don't matter anymore. And that's where we are today almost 40 years after the shah left.

You also discuss the growth of anti-Shia sectarianism in Pakistan and the transition from Zulfikar Bhutto to Zia ul-Haq. Can you explain that a little bit?

Zulfikar Bhutto is a Pakistani Shia himself. He's not interested in the sectarian dimensions of this at all. In fact, when I studied Iranian-Pakistani relations from the 1940s all the way up to the present, you have to travel to the late 1970s—almost 40 years go by where the Sunni-Shia issue isn't mentioned at all in any of the cables coming out of London and elsewhere. It's a non-factor. Nobody cares.

It becomes an issue when General Zia ul-Haq takes over and decides to Islamize Pakistani society the way he thinks it should be done, which is the hard-line Sunni version of Islam, which in turn creates fear among the large (about 20 percent) Shia minority in Pakistan. But remember, Zia ul-Haq takes over in '77 and the shah falls in '79, and if you look at that two-year period and say 'How much fear and anxiety did ul-Haq's policies about becoming more of a Sunni state create in Tehran?' the answer is very little. What the shah worries about is that Zia ul-Haq turns to the Gulf Arab states for patronage or guardianship, whatever you want to call it. It is only after [Ayatollah Ruhollah] Khomeini comes to power in Iran in '79 and who also plays the sectarian card that you see an element of sectarianism becoming more of a practice.

But again, I want to emphasize, even when Khomeini was alive in the 1980s, this is largely limited. When we think about 20 percent of Pakistan's Muslims are Shia, that you have a couple thousand that are joining radical groups doesn't tell me that sectarianism was the number-one item on the agenda.

Why would Bhutto in the early 1970s turn to the Gulf Arab states? This is important. He's a Shia Pakistani leader. He's not driven by the fact that he shares being Shia with the shah of Iran; in fact, he falls out with the shah of Iran. Why? Because he sees the shah of Iran looking down on Pakistan increasingly after Pakistan's defeat against India in 1971, and Zulfikar Bhutto feels the shah thinks he is by nature going to lead the regional hegemon. Pakistan is not happy with that and when the Iranians start basically echoing what the Americans are asking the Pakistanis to do—primarily American demands that Pakistan cease any efforts in pursuit of nuclear weapons—when the shah echoes that American line, from Zulfikar Bhutto’s point of view, then the shah is no longer a partner as such but somebody that's basically conveying Washington's concern to him.

So what does he do? Zulfikar Bhutto turns to the emerging oil-rich Gulf states—the Emirates, Qatar, Saudi Arabia. The fact that he was Shia had nothing to do with it. Bhutto is focused about India: Who can come to my aid, who can foot the bill for my nuclear program that I need to build up because I know that India is just about to get their hands on a nuclear weapon and I cannot lose that military competition on that front? There is no mention from the Saudis, the Emiratis, the Qataris—all of these famously Sunni nations—Oh, we don't like Bhutto because he's Shia, you know? There's no sign of that. This sectarianism is something that unfortunately becomes much bigger of a player in the foreign relations of everybody in the last 15, 20 years because of a lot of other factors.

So much of the relationship was conditioned by the Cold War and in the '70s you talk about that pivot to the Gulf, and the United States consents to it and Saudi Arabia becomes a proxy for the United States to provide aid to Pakistan. How influential was that U.S. endorsement in cementing the Riyadh-Islamabad relationship?

I think the Saudis really initially helped just to help a fellow Muslim state in need. It took a long time for the Saudis to really normalize relations with India to where they are today—relations are OK now—but for a long time the Saudis were much more exclusive in showing that they were on the side of Pakistan in the Pakistan-India wars and conflicts. But the shah of Iran, by 1971, realizes that the future of the Indian subcontinent is more or less going to be controlled by India—because of size, because of its location—and Pakistan will never prevail over India so why put my eggs in the basket of Pakistan?

When the Saudis start providing subsidized oil and all sorts of other financial support to the Pakistanis, instead of just giving them a blank check the way the Saudis were doing, the Iranians started asking the Pakistanis to modify their policies, to tone it down with India, to consider integration into the fold. For instance, when there's talk about economic trade, the Iranians tried their hardest to get the Pakistanis to accept that any economic integration plan that might be reached would lead to income transfers through India, which the Pakistanis vehemently opposed. They didn't want anything to do with that.

The genesis of the Pakistan-Saudi relationship, going back to the 1970s—the Saudis didn't come with so many questions and were almost more innocent in their support of Pakistan. It was a fellow Muslim country that needed help. And the shah of Iran had already by then moved beyond that. He had done all that in the '50s and '60s and they had learned their lesson. What really changes it is, in the 1980s, the Saudis become extremely close to the Pakistanis because of the shared interest with the United States in Afghanistan, in kicking the Soviets out.

I thought that was one of the most interesting portions in the book, the discussion of the proxy conflict between Iran and Pakistan, and by extension Saudi, in Afghanistan starting in the 1980s and going even through the present. You write in the book about how Iran offered to work with the United States in Afghanistan first in 1986 and then again at the Bonn Conference in 2001, and instead the United States worked through Islamabad. Do you think that was a mistake, or was Iran and Pakistan's competition in Afghanistan always so zero-sum as to make that unworkable?

As soon as the mujahedeen started the insurgency against the Soviets, Pakistan and Iran are supporting the biggest cause: to get the Soviets out. But there are a number of factors that make it complicated.

One is that the Iranians do not trust the Pakistanis. Khomeini does not trust Pakistan; Khomeini looks at Zia ul-Haq, this general, as basically another shah, another tyrant that had to be toppled by his own people. Now, Khomeini didn't say 'I will topple you,' but the fact is that he saw the writing on the wall. So there was distrust, there was a lot of distrust.

Afghanistan under full Soviet control would become a platform from which the Soviets could incite all sorts of groups in Iran and Pakistan to stand up against their own respective central governments. But this wasn't enough to get a real consensus between Iran and Pakistan...

And yet there's a shared interest in making sure the Soviets don't consolidate in Afghanistan, because if they did, both Pakistan and Iran would suffer the consequences. Afghanistan under full Soviet control would become a platform from which the Soviets could incite all sorts of groups in Iran and Pakistan to stand up against their own respective central governments. But this wasn't enough to get a real consensus between Iran and Pakistan about what to do against the Soviets.

So you end up with basically two parallel tracks: The Iranians have their proxies they work with and the Pakistanis have their proxies, and it turns out the Pakistanis have far more involvement and were far more critical actors in what happened to the Soviets in Afghanistan because of a number of factors. One is that Afghan society is mostly Sunni, and almost all the Sunni groups decided to park themselves in Peshawar and elsewhere in Pakistan when they were fighting the Soviets. The minority Shia had movements in Iran in the beginning, but in terms of numbers they were always the minority. And don't forget, this is the period Iran is engaged in its bloody war against Iraq, so the Iranians don't really have much capacity at all to do much. They turned themselves into a pariah state [with] their own decision to turn away from both the Soviet Union and the United States and say, We don't want to be part of this Cold War, we're going to go our own, solo way. The Iran-Iraq war imposed heavy costs on them, which means their ability to really financially do much anywhere else outside the Iran-Iraq war is extremely limited. They tried to be involved in the mujahedeen campaign against the Soviet Union, but at a much lower level or volume than Pakistan. The Pakistanis basically have a free-for-all, they have American support in terms of giving arms, whatever they want; they have the Saudis and others foot the bill; and there you go, they're in a position to be much more influential and they are. And this is really in many ways accepted by the Iranians, because during the Geneva U.N. peace talks involving Afghanistan, the Iranians would freely admit that they were going to be represented by Pakistan. They didn't see the point in sending anyone to the talks.

Now, once the Soviet Union pulls out in 1989, what you end up with is the real proxy war. Even though in the '80s there was tension between Pakistan and Iran—they were suspicious perhaps of one another, there was plenty of fighting going on—but there was no need for them to lock heads. By the time the Soviets pull out, the Iranians are done with the Iran-Iraq war and they are now extremely concerned about long-term Saudi-Pakistani plans for Afghanistan. This is the beginning of the real proxy war, which takes place throughout the 1990s, until the fall of the Taliban in 2001. The Iranians look at Afghanistan, which they had previously seen as a dangerously exposed place that could become a jumping board for so many influences in the region, and see the Soviets replaced by Pakistan, which allows the Saudis to take over and pose a threat to Iran from the east. This is when the Pakistan-Iran competition for Afghanistan takes off and, I would argue, some 15 years after the Taliban fell, we're still pretty much there. They’re still looking at the place in the view of some game and both sides want to maximize influence in that country.

How much is the Iran-Pakistan proxy conflict still shaping Afghanistan today? Can you talk about how this is playing out in the present?

I think it's really difficult to measure exactly the role the Iranian-Pakistani conflict has in preventing Afghanistan from becoming a peaceful place. I wouldn't blame that all on Iran and Pakistan. The fact that Iran and Pakistan and many others look at Afghan soil as a place to go in and pursue these geopolitical ambitions—Iran and Pakistan aren't alone in that. China's there, Russia's there, the Gulf Arab states are there, clearly the United States is there.

It's complicated, but it also shows you one of the real dilemmas. There are so many Afghan actors inside Afghanistan that are looking for a share, that are inviting outsiders to basically help them in their respective inter-Afghan rivalries. That just makes the whole challenge of putting this Afghan war, civil conflict, whatever you want to call it—to put it back again really would almost require all these outside actors to step back and have some sort of agreement that they're going to push the Afghan actors instead of inciting them to fight one another in order for Iran to score points against Pakistan and Saudi Arabia. Instead of doing that, they choose 'We're not going to help these Afghans we've hosted all these years until there's some sort of regional or international consensus that we all urge them to do the same thing,' which is to work toward peace. We have no indication that these various foreign actors are on the verge of leaving Afghanistan. It seems to be everybody's sitting there waiting for the United States to pull out; if the U.S. pulls out, then they're going to get back to where they were before the 1990s. They'll support their various militant groups, hoping that they're going to win. And in that way, it’s not that dissimilar to what we see in Syria today.

You clearly went through a bunch of diplomatic cables in writing this book. Do you have a favorite anecdote that you found from those?

The one that for me was very fascinating was when Bhutto goes to the White House. He says, Look, you guys, you Americans really have a lot of hope for the shah of Iran and I can't say that's wrong, but I can tell you that he's not on such stable ground and maybe you should reconsider your approach to Pakistan. Maybe we can be much more of a formidable pillar for American policy in Asia than if you focused solely on the shah.

Now what Bhutto didn't know was that the Americans went straight to the shah and told him what he had said. That brings that close relationship the shah had with Bhutto crashing down. Bhutto finds out the Americans have told the shah what he had said and, to his very end, when Bhutto is in that prison cell knowing that Zia ul-Haq is about to hang him, and knowing that very few people out there could put pressure on Zia ul-Haq, he keeps thinking, What if I hadn't said those things about the shah? Because he had this suspicion the shah could have done a lot more to help Bhutto get out of that prison cell and avoid the hanging if the shah wanted to. To his very last moments he's thinking, This all comes back to what I said all those years ago, four years earlier in the White House. He writes it in his memoirs; he writes, This is the shah getting back at me.

This is his interpretation, obviously. We don't know if Zia ul-Haq would have done anything if the shah had pushed him, but certainly Bhutto kicked himself, thinking that sometimes you can be too frank and regret it. But it also shows to me the role of personality in shaping something so critical as the relations between these two countries, Iran and Pakistan.