Here's What You Need to Remember: Contemporary Iran is no Persia. It lacks the economic and military resources for enterprises of such sweep. And without that overbearing power, it stands little chance of overawing others into bandwagoning with Tehran and doing the mullahs’ bidding.

When pondering some strategic quandary you can get oriented by postulating what the greats in the field would say about it. What they said or wrote about roughly similar circumstances furnishes clues to what they might say about today’s strategic conundrums. This is the beginning of wisdom. The classics seldom furnish ready-made solutions. They almost always furnish a platform for launching into original thought.

Yes, you have to be humble when extrapolating from someone else’s words. Time, technology, and human society march on, and it’s hard to say for sure what some figure from the past would make of material and social trends since then. And yes, avoid treating their writings as gospel. To be great is not to be infallible. Sometimes sages get things wrong—even in their own time.

Still, situations rhyme between ages while principles endure. Ideas from the strategic canon retain their power to help posterity make sense of today’s controversies. Case in point: Iran is much in the headlines of late. What would the legendary geopolitics scholar, Yale professor Nicholas Spykman, say about the sputtering confrontation between the United States and Iran?

He would have plenty to say about the feud, first and foremost that Washington should continue trying to blunt Iranian ambitions. Not for him the passive approach. He was no proponent of “offshore balancing,” the conceit that America should stay mostly aloof from foreign entanglements, sending armadas and armies across the broad main only if inhabitants of the Far East or Western Europe proved unable to withstand a domineering power—an imperial Japan, a Nazi Germany, or a Soviet Union—on their own.

Spykman faulted administrations from both political parties for remaining diplomatically and militarily quiescent during the interwar years. They had allowed dangers to fester, and through neglect had compelled the United States to fight a second world war scant decades after the first. He found this unacceptable. Spykman harbored little desire to go abroad in search of monsters to slay. He wanted to go abroad to confine monsters to their lairs.

Or, better yet, he believed proactive U.S. involvement would keep predators from gestating in the first place. Acting early and forcefully would prevent would-be hegemons from conquering the “rimlands” of Western Europe and East Asia. They would find it hard to lash out at the Americas across the Atlantic or Pacific without the resources from those rich regions. No brute would need slaying if the United States made common cause with opponents of aggression ahead of time.

In other words, Spykman was an onshore balancer. But does his forward strategy apply to the Persian Gulf region today? For it to do so the Islamic Republic must be a Middle Eastern counterpart to Germany, Japan, or the Soviet Union—a powerhouse driven to unite the Gulf region or South Asian rimland under its yoke, harvest the resources it acquired to build up martial might, and hence constitute a menace to the New World.

Yet Iran falls woefully short of hegemonic status. Iranians certainly long for the glory days when the Persian Empire bestrode the Middle East and South Asia and, for a time, even threatened to bring Europe under the Great Kings’ suzerainty. Contemporary Iran is no Persia. It lacks the economic and military resources for enterprises of such sweep. And without that overbearing power, it stands little chance of overawing others into bandwagoning with Tehran and doing the mullahs’ bidding.

In other words, the prospects for an imperial Iran appear dim. Survey the region through Iranian eyes. To the west, you will espy the Gulf Cooperation Council (GCC) countries. None of these Sunni Arab states could stand up to Iran in a one-on-one scrap. Collectively, though, they field serious military power funded by oil wealth that—unlike Iran’s—is unencumbered by economic sanctions. The GCC promises to remain a formidable contender so long as its members stand together.

Even if all sanctions disappeared today, it would take the Islamic Republic decades to rejuvenate the economy, amassing national wealth and transmuting it into military prowess and diplomatic clout sufficient to coerce this standing Arab coalition. Tehran’s capacity to steamroller the Gulf region or intimidate the GCC states into submission seems doubtful.

To Iran’s northeast lies Central Asia, while to its southeast lie Pakistan and India. Afghanistan and its neighbors are strategically inert at best. If Tehran covets an alliance with them, let’s cheer it on. Such allies would be dead weight rather than an asset to Iranian strategy. Pakistan fronts on the Arabian Sea, along the approaches to the Strait of Hormuz, and boasts a nuclear arsenal. Geography and the military factor make it a more viable partner for Iran. Still, that’s pretty weak adhesive to cement an alliance between Shia Iran and Sunni Pakistan.

Most importantly, India is the resident hegemon of South Asia and overshadows Iran by diplomatic, economic, and military measures. The idea that New Delhi would submit to Tehran’s will or join it at the head of an anti-Western alliance verges on whimsy.

In short, it’s tough to posit any realistic scenario whereby the Islamic Republic overruns its near abroad or attracts a serious alliance—staging a Middle Eastern equivalent to the German or Japanese conquests that spurred Nicholas Spykman to enunciate his forward strategy. And even if Tehran did manage such an improbable feat, would success empower it to reach out and smite the New World? Color me skeptical.

Look at the map again. Gazing out from American seacoasts, the Indian Ocean region is a faraway and inaccessible theater by contrast with Western Europe and East Asia—rimlands from which a hostile power would enjoy direct and uncluttered routes to American rimlands. Iranian forces would have to travel much farther than forces based in Europe or the Far East. Furthermore, maritime geography would force them to transit nautical chokepoints to exit or reenter the Indian Ocean—and it’s a straightforward matter for some foe to contest passage through straits and kindred narrow waterways.

The verdict? Iran clearly boasts enormous capacity for mischief-making, it clearly relishes tweaking the Great Satan, and it has options. For example, Tehran will probably develop a modest nuclear arsenal over time. Doomsday weaponry would give U.S. rimlands strategy in South Asia a twist that Spykman—who perished before the atomic bombings of Hiroshima and Nagasaki—could never have foreseen.

Alliance making and breaking represent another option. Tehran can court fellow opponents of American dominance, chiefly China and Russia, and bog down U.S. forces at a time when Washington prefers to apply itself to great-power competition in the Indo-Pacific and Atlantic rather than some Middle Eastern bywater. It can try to divide the West against itself, as it has sought to do for many years. And on and on.

All the same, the ghost of Spykman can rest easy with regard to the southerly rimlands. Iran is a troublemaker for sure. But it is neither 1914 nor 1939 in the Gulf region.

Now, it’s possible this relatively upbeat strategic diagnosis and prognosis would leave Spykman feeling conflicted. If he accented the imperative to manage events in intermediate zones joining the sea to the heartland, he also acknowledged that a distant maritime power must command the sea in order to execute a balancing strategy in Eurasia. Maritime command is a necessary enabler. Lose command, you lose access; lose access, you lose your ability to project armed might; lose your military say-so, your rimlands strategy fails.

History amply demonstrates the importance of access. Spykman observes that Great Britain basked in an empire on which the sun never set precisely because its Royal Navy ruled the “girdle of marginal seas,” semi-enclosed bodies of water that lap against the Eurasian periphery. These seas gave Britannia conduits for projecting influence and control onto remote shores. Expanses such as the Mediterranean Sea, the South China Sea, and, yes, the Persian Gulf are inlets into the Eurasian landmass. From their confines, a dominant navy can radiate military and thus political power deep inland.

Today they are American conduits, and central to any Spykmanesque balancing strategy. But if coastal states could bar the U.S. Navy—today’s answer to the world-straddling Royal Navy of yore—from the marginal seas, they could vitiate Spykman’s maritime geostrategic vision. Or even if local defenders failed to deny access altogether, they could make it costly and treacherous for American task forces to venture into near-shore waters. U.S. officials would think twice before paying a heavy price in lives, ships, and planes. They might blanch unless the need was truly dire.

Even partial success at access denial, then, would work to Iranian strategic advantage. If Washington did balk at dispatching naval forces to the Gulf region or its approaches, Tehran would have deflected U.S. efforts to project power; discredited U.S. alliance commitments to neighbors Iranian magnates wanted to cow; and in the process won the freedom to pursue power and influence by such means as clerical leaders saw fit to deploy. Turns out mischief-making advances larger purposes.