Aaron David Miller

Opinion contributor

Tensions in the volatile U.S.-Iran relationship are increasing, and the two sides are ever closer to the possibility of a direct military confrontation since President Donald Trump condemned what was almost certainly an Iranian mine attack disabling two oil tankers in the Gulf of Oman last week. A serious and sustained conflict isn’t inevitable, but the odds have increased.

How did we get here and, more troubling, exactly where are we going? Amidst all the hype, spin and storytelling from both sides, here are some harsh truths about the Trump administration and its Iranian adversaries.

The Iranian regime is authoritarian, ideological and repressive, a serial human rights abuser and regional troublemaker. But we now find ourselves in a dangerous situation largely as a result of a great unraveling begun by the Trump administration's unilateral decision last year to withdraw from the 2015 Iran nuclear agreement.

The accord — known as the Joint Comprehensive Plan of Action (JCPOA) — was flawed, to be sure, and didn’t address Iran’s aggressive regional behavior or its ballistic missile programs. Even so, it was still a highly functional arms control agreement that imposed significant constraints on Iran's nuclear program for at least for a decade or more.

'Maximum pressure' and no Plan B

Campaigning hard against the agreement, candidate Trump vowed to renegotiate or leave what he deemed the worst agreement ever negotiated. Then as president, he pulled out of the agreement and launched his "maximum pressure" campaign. The administration reimposed sanctions on banking and petrochemicals and, in the past several months, has made a major effort to reduce Iran's lifeblood — its oil exports — to zero. As intended, all of this has wreaked havoc on the Iranian economy.

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Not surprisingly, the regime, which the Iranian foreign minister quipped had a Ph.D. in sanctions busting, signaled through mine attacks on six oil tankers in the past month that it had options, too. Within hours of Thursday's attacks, oil prices spiked. No matter how egregious the regime’s behavior in other areas, pulling out of the JCPOA without a Plan B other than "maximum pressure" has more than any other factor brought us where we are today.

Tensions rising but caution on both sides

With no anchor stabilizing relations between Washington and Tehran, and mistrust at an all-time high, the dynamic has become one of drift and deterioration. Given the bellicose rhetoric on both sides since the start of the Trump presidency, it’s stunning that there hasn't been a clash already in Syria, Iraq or the Persian Gulf. But that impulsiveness in words has not been reflected in deeds, revealing the caution with which both Trump and Iranian Supreme Leader Ali Khamenei exercise in order to avoid a major escalation — at least so far.

Trump has repeatedly expressed his desire to meet with Iran's leadership and, given his campaign promises, wants to avoid another costly war in the Middle East — despite his hard-line national security adviser John Bolton, who would like the regime bombed if not overthrown.

Khamenei is determined to put regime survival ahead of all else, particularly given his advanced age, health concerns and an unresolved succession. He is wary of the unpredictability and uncertainty that would accompany a major war with America. He must also contend with an Iranian Revolutionary Guards Corps itching for a fight.

And so Khamenei and Trump test each other — Trump piling on sanctions and deploying naval and air assets to the region; Khamenei signaling through Revolutionary Guards attacks against oil tankers (sparing U.S. targets so far) that Iran has a vote, too. There has been no casus belli serious enough to trigger a direct attack by either side.

Does Trump have an Iran endgame?

A major escalation can't be counted out, however, largely because there is little to stabilize the situation. The Iranian economy is hurting badly with little sign of serious relief from well-intentioned Europeans who would like to provide it but are worried about violating and getting slapped with U.S. sanctions.Oil revenue has been severely cut, and Iran’s inclination to wait Trump out is not really a strategy or a means to relieve the pressure. Iran has abided by the nuclear accord’s major provisions but also has threatened to begin higher-level enrichment of uranium unless it gets some economic relief.

As for the Trump administration, its endgame strategy is unclear, as is whether there even is one. Secretary of State Mike Pompeo says regime change by military means isn’t the goal. But Bolton seems to be angling for regime change through political and economic pressure — a seemingly fantastical goal. Trump would clearly like a negotiation, but even he admitted in light of recent tensions that the time is not right for a deal. The administration publicly asserts that its goal is to get Iran back to the negotiating table to fashion some new agreement, but is it prepared to make the serious concessions Iran would demand? Is Tehran even interested?

No Trump plan: A year after ditching Iran nuclear deal, what is Trump's Iran policy? Saber rattling?

At a minimum, the two sides are badly in need of a hotline or channel to deconflict their military forces in the region in order to preempt a serious escalation. During the Obama administration, the Iranian negotiators reportedly rejected such a proposal. And they may not agree now, seeing it as a sign of weakness when they want to keep the pressure on.

The cruel reality is that it may well require more tension, perhaps even a U.S.-Iranian clash, to convince each side that the situation has become too dangerous to continue. But once direct conflict begins, it might be impossible to stop. Sadly, the headlines of the U.S.-Iranian crisis look bad, but the trend lines look even worse. Washington and Tehran seem headed sooner or later for a blowup, and one would be hard-pressed right now to figure out how to preempt it.

Aaron David Miller, a distinguished fellow at the Woodrow Wilson International Center for Scholars and a former State Department adviser and Middle East negotiator, is the author of "The End of Greatness: Why America Can’t Have (and Doesn’t Want) Another Great President." Follow him on Twitter: @aarondmiller2