We've rarely admitted it, but the debate in the United States over the Iran nuclear deal, which formally began this Saturday as the world lifted many sanctions on Iran, was never really about nuclear weapons. Not primarily, anyway.

Sure, the nuclear deal itself has a lot to do with nuclear weapons. But it should tell you something that America's debate over the deal is still raging even after Iran has disassembled the bulk of its nuclear program, and that we're now having nearly identical arguments about the US-Iran prisoner swap and the US-Iran boat incident.

"The Iranian nuclear program is not really what opponents and proponents of the recent deal are arguing about," Jeremy Shapiro, of Brookings, wrote nearly a year ago, and it's still true. It's never been about nukes or boats or prisoners but rather whether America should deal with Iran at all. Is this, to paraphrase Margaret Thatcher's famous quote about Mikhail Gorbachev, a country that we can do business with? And that question itself hits on divisions in US foreign policy that go way beyond this one county and are much older than this one issue.

Iran has become the subject of America's most heated and divisive foreign policy debate in perhaps a decade. But the vitriol is driven not just by competing readings of Iran, or even by partisanship, but by a confluence of deep and long-running disagreements over fundamental questions of America's place in the world.

There are, to my eye, three distinct and separate divisions in American foreign policy that are playing out here. If you'll forgive a bit of jargon coinage — an ancient and glorious tradition among pundit types — we might term those divisions: pragmatists versus hegemonists, diplomats versus militarists, and Middle East reformists versus Middle East status quo-ists.

Those debates have been raging, in one form or another, for years or decades. In the past, sometimes they've overlapped and sometimes not; the distinctions were sometimes clear and sometimes fuzzy. But Iran is bringing out all three, more sharply and clearly, than has any issue in years.

Because we're really having these three arguments at the same time, and because they are all long-held disputes now playing out simultaneously, everyone is talking past one another — and because it's not even remotely just about Iran, none of these disputes are about to settled. But once you see them, this debate and its vitriol start to make a lot more sense.

Pragmatists versus hegemonists

The pragmatists see compromise and conciliation, toward Iran and more broadly in the world, as the most responsible way to maximize America's interests while minimizing risks and costs. They are averse to overextension and willing to write off some problems as too costly for the US to wade into. They include President Obama as well as former President George H.W. Bush, both realists willing to use or threaten limited force but only when it can achieve clear, specific aims.

In this view, if Iranian and American interests can be made to coincide, whether through diplomacy or coercion or both, then dealing with even an adversary like Iran can achieve American interests while also minimizing risks such as war.

The hegemonists tend to see any challenge to American primacy in the world as a threat to the American-led liberal international order itself. In this view, American dominance promotes peace and makes the world safe for democracy — allowing that dominance to wane thus risks inviting chaos and tyranny. This existential battle between America and those who threaten its hegemony animates, in their eyes, nearly every international crisis. The hegemonists include Ronald Reagan but also, at many points, Jimmy Carter, whose 1980 "Carter Doctrine" declared the US would use military force to protect its economic interests in the Persian Gulf.

In this view, hegemony is about perception as much as about hard tools like tanks or missiles. Therefore, it is necessary to stand down every challenger, not for simple reasons of ego or pride but because even appearing to waver is a de facto surrender that imperils America's not-at-all-guaranteed dominance. Iran isn't just one middling country, but potentially the start of a global anti-American uprising that could overturn the world as we know it. Whether America happens to come out ahead in specific negotiations is not the point; negotiating in itself legitimizes Iran's challenge to American dominance.

Pragmatists see American power as a tool, sometimes useful and sometimes not, whereas hegemonists see American power as a good within itself, something to be protected and promoted however possible, and that by disuse will erode.

The Iran-US sailors incident is a perfect example of this division.

To pragmatists, the incident was defused and deescalated quickly and relatively painlessly: All 10 sailors were freed within a few hours, and the only cost was that Iran released embarrassing photos of the sailors being detained. That trade-off, on balance, seems great for the US. But, to hegemonists, that embarrassment did real-world damage to US interests by giving the appearance of Iranian strength overpowering American weakness, which thus invites more such challenges that could eventually see the entire Middle East turned against us.

On Iran more broadly, pragmatists see decades of enmity that has been costly for the US and brought little benefit, whereas a smidge more compromise and even cooperation will not just serve US interests but also reduce the costly risk of war. But hegemonists see an Iran that has always been, and always will be, an imminent threat to America's hegemony over the Middle East that can only ever be countered with all American tools of power, including the credible threat of war.

Diplomats versus militarists

Every administration uses some combination of diplomacy and militarism, whether it's the threat of force or its actual use, to achieve its aims. The disagreement here isn't about which to privilege. Rather, it's a disagreement over how adversarial regimes like Iran are likely to respond to those tools.

And it's a disagreement about what kind of global power America is supposed to be: a power that guides through consensus and coalition building, versus a power that leads unilaterally and, if necessary, dominates through strength.

For the diplomats, the US can best achieve its goals by making sure other countries' interests line up with its own, whether those countries are allies or not. They're not just willing to work with adversaries but often desire it, seeing it as a way to decrease hostilities. And it often means working within other countries' domestic politics, trying to shape them such that they'll be more likely to bend their countries in our direction.

Presidents who've thought this way include Bill Clinton, who famously intervened in Israeli politics to promote candidates who'd be more sympathetic to American goals; and George W. Bush, who tried to establish personal bonds with foreign leaders from Nicolas Sarkozy to Vladimir Putin. Most famous, of course, was Richard Nixon, who was more than happy to align the US with adversaries, even communist China, when they could find mutual interests.

The militarists, on the other hand, see a world neatly divided between allies and adversaries in a zero-sum contest for influence. America's role is strengthening itself and its allies at the cost of its enemies. In their views, enemy states' overwhelming goal in the world is to counter and reduce American influence. Therefore, any negotiation is folly because enemies will never compromise on their ultimate agenda of weakening America and its allies. Because enemies are innately hostile and everything is a zero-sum competition, military strength is America's greatest asset.

Famous militarists include Dwight Eisenhower, who saw communism as a monolithic force bent on world domination, leading him to intervene in Vietnam rather than work with the revolutionary communist leaders who had in fact reached out to the Americans; as well as Ronald Reagan, for whom the Soviet Union was not motivated by complex interests or domestic politics so much as by the twisted ideology of an "evil empire."

The diplomat-militarist divide is widest on Iran. Diplomats see a country with complex and noisy internal politics that could be on the verge of a major shift; they also see a rational state whose interests can be shaped to clash less severely with America's. Militarists, however, see an innately and implacably hostile enemy at best, and at worst an irrational "death cult" akin to Nazi Germany. For militarists, it is essential to not only confront Iran as directly as possible, but to provide unflinching assistance to American allies who also oppose Iran, to demonstrate a unified front.

This is the divide, in particular, that has had much of the Washington foreign policy community at one another's throats over the past year. Diplomats are aghast at the militarists who would refuse a rare opening to peacefully reduce hostility with Iran. Militarists cannot believe how naive the diplomats are to believe that Iran could ever be driven by anything other than an unquenchable anti-Americanism; they see Iran's internal politics as a nation-size ruse meant to trick Americans.

It's an argument that neither side can ever win, because it's not really about the intricacies of Iranian politics or the merits of the nuclear deal. It's about the way in which you see the world and America's role in it.

Middle East reformists versus Middle East status quo-ists

America's obsession with the Middle East goes back decades: to the oil crisis, to the 1979 Iranian Revolution, to the 1990 Gulf War; starting in the 1980s, the religious right developed a preoccupation with Israel and thus the Israel-Arab conflict. The 2001 terrorist attacks and the 2003 Iraq invasion guaranteed at least a generation of heavy American involvement in the region.

So there is a real sense in the US, and indeed in Middle Eastern capitals, that America owns this mess of a region and that it's America's responsibility to deal with it. For a few years after the Iraq invasion, it was hard to have an open debate about this because those who'd advocated for the invasion felt compelled to argue that everything was fine. Now that we've had two successive administrations oversee the region's deterioration, it is finally a bipartisan consensus that the region is in severe crisis.

In the rare moments when people can put aside arguments over which American president is more to blame, their disagreements often boil down to one core issue: Is it better to rebuild and reinforce the status quo in the Middle East or to reform the regional order in some new way that will make it more likely to survive?

For the status quo-ists, this often comes down in part to Israel. America's closest ally in the region is well-served by the status quo, in which the Middle East is dominated by secular dictators whose countries once waged war on Israel but have mostly come to make peace with it. Those dictators are the heart of this worldview: Status quo-ists appreciate their reliability and fear that a democratic Middle East will empower Islamists and populists who oppose the United States.

The reformists don't really have a specific plan for how to change the Middle East so much as a sense that it has to happen. Dictatorships are unstable and can topple suddenly and violently; the region's division between Saudi-backed Sunni powers and Iran-backed Shia powers has fueled much of the last decade's violence. The reformists tend to be skeptical of America's most powerful Mideast ally, Saudi Arabia, and to suspect that Iran is going to rise in power whether we like or not, so it's better to shape that rise as best we can.

There is a lot of mutual suspicion here. Reformists see the status quo-ists as trying to build American strategy on a foundation of quicksand, and wonder why they're so eager to embrace Saudi monarchs who behead dissidents and an Israeli right that has long defied American presidents of both parties. Status quo-ists, meanwhile, suspect that the reformists are at best seeking America's total surrender from the region and at worst trying to engineer a Middle East dominated by our enemies.

Iran is at the center of this argument: Everyone agrees that Iran is ascendant and America's Sunni-dictator allies are struggling. The question becomes: Should America throw itself into reversing those trends, or accept them as inevitable and try rather to shape them in a way that will be tolerable?

The reformists, to be clear, don't want to ally with Iran, but rather to minimize hostilities and try to shape Iran's behavior to be more productive, while also building up America's allies. But status quo-ists see this as tantamount to surrender, and believe the US should be wholly focused on stopping or reversing that rise.

This is a relatively new debate; it has only really opened under George W. Bush and, to a much greater extent, under Obama. Both have approached the Middle East as reformists, seeing the status quo as untenable. Though whereas Bush sought to deliberately spark the region's complete transformation by toppling Saddam and promoting democracy, Obama's view is that the Middle East is changing under forces and pressures beyond American control.

Today you can see this division playing out among the presidential candidates, and it's not along partisan lines. Status quo-ists Ted Cruz and Bernie Sanders have both stated strong support for America's authoritarian allies in the region.

Meanwhile, reformist Hillary Clinton supported the nuclear deal with Iran and has warned that Middle East dictatorships can't last. Marco Rubio has challenged those dictatorships as well, though he is more akin to second-term George W. Bush in wanting to see Middle Eastern politics transform but preserve its regional power balance.

The Iran debate will never, ever be settled

Looking over these three disagreements and how they are playing out over Iran, the point is that none of them is remotely partisan. And none of them is about to be resolved; they are differences in philosophy that can be argued for or against but will probably always be part of the American foreign policy conversation.

This is why you have seen, over the past year, many members of Washington's foreign policy community argue themselves red in the face. They can cite as many facts about Iranian nuclear cuts, or about Iranian funding for terror groups, as they want. They can debate the nature of Iran's moderates or the likely fate of its supreme leader all day. Such narrow questions are simply not what these arguments are really about.

Rather, it's an argument about conflicting worldviews and readings of American power and ambitions for the Middle East. Even if we were to fully acknowledge that's what we're arguing about, those disagreements are fundamentally irresolvable, which is why they've been with us for decades. And they'll continue to be with us for decades.

Iran will not always be at the center of those debates, but it will probably feature heavily in them for as long as the Middle East is in chaos, which is likely to last decades. So you can expect to hear the same arguments over Iran for, if not the rest of your life, at least a big chunk of it. Just know that while people might refer to Iran a lot in those debates, they're really talking about something much bigger.