Tension is mounting between Washington and Tehran with Thursday's shooting down of a U.S. drone by Iran's Revolutionary Guard. What would a U.S.-Iran war in the Persian Gulf look like? It’s worth trying to envision the contours of such a maelstrom before America drifts into one. If the U.S. entangles itself in a conflict it ill understands, it could find its war aims eluding it, hazards mounting and costs spiraling beyond anything the Trump administration or American society relish — or even contemplate — paying.

Let’s ask the greats of strategy. Martial sage Carl von Clausewitz counsels commanders and their political masters that “the first, the supreme, the most far-reaching act of judgment that the statesman and commander have to make is to establish … the kind of war on which they are embarking; neither mistaking it for, nor trying to turn it into, something that is alien to its nature.”

Or, in plainspoken English, if you don’t know what you’re getting into, your chances of getting out of the enterprise with what you want range from slim to none. Things will be even worse if, like combatants throughout military history, you insist on fighting the fight you prefer to fight while disregarding the arena and antagonist actually before you. To give the uplifting words from John F. Kennedy’s inaugural address a depressing twist: Without that basic understanding, you’re apt to pay a heavy price and bear a crushing burden for little meaningful return on your investment.

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Foresight now keeps things in balance later.

No one should plunge into a maritime war lightly. Naval enthusiasts like to tout the rousing high-seas triumphs history has produced — the battles of Trafalgar or Leyte Gulf — but the dirty little secret of saltwater combat is that it seldom wins wars. Still less do navies win them in quick or decisive fashion. A century ago the British naval historian Julian Corbett observed that sea warfare can only defeat an enemy through “gradual exhaustion” that may exhaust a country’s domestic constituents or foreign allies and friends before it exhausts the enemy.

After all, naval warfare is economic warfare. Its goal is to bar not just hostile navies but hostile merchant fleets from the briny main. Industry depends on mercantile shipping to sell wares abroad and generate tax revenue for causes the government and society deem worthwhile. Attack enemy shipping and you decimate the enemy’s income from seaborne trade and commerce, and thus its warmaking potential. Less tax revenue, fewer armaments; fewer armaments, dimmer prospects on the battlefield.

What’s not to like?

But as Corbett notes, meddling with the sea lanes — the nautical thoroughfare connecting producers with consumers — disrupts the flow of trade for foe and friend alike. Detaining a vessel on the high seas to determine its identity costs the shipowner time and money, even if the vessel is flying a friendly or noncombatant flag and soon proceeds along its way.

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That’s mere annoyance, though. Suppose the opponent, such as Iran, overshadows a narrow sea route where shipping bearing precious commodities must pass. And suppose that opponent is prepared to cut loose indiscriminately against shipping. Iran boasts a conventional navy able to make trouble in the Strait of Hormuz and its approaches, backed by a panoply of shore-based aircraft and missiles able to strike out to sea. Traditional forces furnish Tehran a direct option for raiding sea traffic.

Also in the maritime mix is the Islamic Revolutionary Guard Corps Navy, an irregular force of armed speedboats and light surface craft meant to harry shipping in the Islamic republic’s “near abroad.” And if that’s not enough, Tehran sponsors a variety of militias and terror groups capable of offshore troublemaking. Not only do surrogate forces allow Iran to make mischief, they also allow it to deny responsibility for the mischief thus made. That appears to have been the case with assaults on Norwegian and Japanese merchantmen in regional waters this week.

The costs of irregular warfare at sea could prove frightful — measured not just in damaged hulls but in skyrocketing insurance rates and in higher prices for cargo that firms must then pass on to customers. Exorbitant prices are bad for everyone.

Would such measures bring Iran outright victory? Doubtful. For one thing, the mullahs would be picking a fight with the world. Not only do economies across the globe depend on Persian Gulf oil and gas, some 33 nations take part in a standing Combined Maritime Force founded to keep order at sea in the Gulf region and northern Indian Ocean. Indiscriminate attacks would cry out for multinational countermeasures — and, in all likelihood, render Iranian gains fleeting. The politics works against the Islamic republic.

From a purely military standpoint, a Gulf war would be a scattershot affair, like most marine trials of arms. Each side would try to grind down the other through tactical actions as opportunity arose. Iranian or Iranian-backed forces would lash out at passing merchantmen, much as they did during the “Tanker Wars” in the 1980s. In reply, guardians of free navigation would blend defensive with offensive action. They would assemble merchant ships into convoys protected by escort warships, presumably corvettes, frigates or destroyers. Meanwhile, they would strike at irregular forces’ lairs, and potentially at naval harbors and shore airfields and missile sites, with the hope of squelching the problem at its source.

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In other words, the combatants would snipe away at each other in small-scale actions strewn across the map, hoping to grind each other into submission over time. This is what Admiral J.C. Wylie, one of my predecessors on the Naval War College faculty, would classify as a “cumulative” form of sea combat. This is war by statistics. The sinking of an individual tanker or speedboat doesn’t inflict decisive damage, let alone compel the government suffering the damage to capitulate in the war. But losing lots of ships to pinprick actions could add up to unbearable pain if the bloodletting continues over time.

Cumulative operations, them, strive to kill by a thousand cuts. Like Corbett, and on similar grounds, Wylie is skeptical that any combatant would persevere with such a campaign long enough to see it through to victory. It’s exhausting. Instead, commanders and political leaders would opt for more direct, decisive measures to try to keep the costs and perils of sea warfare bearable. Wylie calls these “sequential” operations, in that forces proceed from point A to point B to point C until the foe cries uncle or no longer can resist.

Tehran has no obvious sequential option; it cannot defeat the world. Washington can entertain a sequential option, but it presumably would involve crushing the Iranian armed forces and, perhaps, unseating the regime in Tehran. That’s a drastic departure from a limited war at sea. If the Trump administration wants to keep any clash of arms short and relatively inexpensive, it should give careful forethought to such an escalation — an escalation that might, in Clausewitzian parlance, transform a limited war at sea into something alien to its nature. Corbett and Wylie could only nod their agreement.

Always consult the masters of strategy before launching into military adventures.

James R. Holmes is J.C. Wylie Chair of Maritime Strategy at the Naval War College. The views voiced here are his alone.