Opinion | Trump Might Not Want War With Iran. Without Diplomacy He Will Get One.

The United States was quick to blame Iran for last week’s attack on two tankers in the Gulf of Oman. Iran has denied involvement, and there is considerable skepticism around the world about American claims. We don’t yet know what really happened, and may not for some time. But what the attacks and subsequent fallout show — regardless of who carried them out — is that President Trump’s policy of “maximum pressure” is not working.

If Iran was behind the attacks, then American pressure has failed to bring it around for renewed talks and has instead prepared Iran for conflict. If the United States cannot provide clinching evidence of Iranian culpability, its eagerness to assign blame looks like a ruse to start a war.

President Trump may not want war, but he will get one unless he balances coercion with diplomacy. He has discredited moderate voices in Tehran who had fought for the nuclear deal and the promise of engagement with the West. Iranian hard-liners, who distrust the West, want out of the nuclear deal and argue that only show of force deters Western aggression, are ascendant.

Iranian leaders think that the United States has cheated Iran and walked away from the deal to strangle Iran’s economy, break its state and force regime change. President Trump’s goal all along has been to negotiate a more stringent nuclear deal with Iran, scuttle its missile program and reduce its regional footprint.

Iran has been surprised by the effectiveness of new American economic sanctions, which are isolating the country and imposing severe hardship on its people. European powers, China and Russia have paid lip service to protecting the nuclear deal but have been reluctant to stand in the way of American pressure.

President Trump expects that Iran will be forced to the negotiating table; others on his team want to keep squeezing Iran until the Islamic Republic implodes. Iranians interpreted the quickness of the Trump administration to lay blame on them for the Gulf of Oman attacks as proof that Washington wants war to dislodge the Islamic Republic.

Iran is keen is to show that bullying tactics will not work. Tehran has met maximum pressure with maximum resistance, first refusing to leave the nuclear deal and then threatening to restart its nuclear program. On Monday, Iran’s Atomic Energy Organization announced that it will break the uranium stockpile limit set by the nuclear deal in 10 days and warned that Tehran could enrich uranium up to 20 percent, a step away from weapons-grade levels.

And Iran’s military posture in the Persian Gulf has become more menacing, seeking to deter American action and preparing for war if that fails.

Iran may be banking on the assumption that unlike some of his key advisers, President Trump does not really want war. Even if they can avoid war, Iranian leaders know a stalemate is untenable. The economic chokehold on the country risks social upheaval, and if it does not come to that, it augurs a future for Iran not unlike that of Saddam Hussein’s Iraq, a weak and broken state ravaged by prolonged economic isolation.

The only option left is to talk. Mr. Trump has broadcast his wish to talk to Iran and has sent messages to Tehran through high-level Swiss, Omani and Japanese interlocutors. He says he does not want war and is not after regime change. At his press meeting in Tokyo he said Iran could prosper under its current leadership.

But Iran’s leaders have publicly rebuffed Mr. Trump’s overtures. They don’t trust him or see a satisfactory outcome to negotiations, especially if they will have to deal with National Security Advisor John Bolton or Secretary of State Mike Pompeo.

Yet the Iranians were keen to hear what Prime Minister Shinzo Abe of Japan had to say on behalf of Mr. Trump. We have yet to learn what Mr. Abe heard back behind closed doors in Tehran.

The challenge for Iran is how to come to the table without the appearance of capitulation, without admitting that Mr. Trump’s maximum pressure has worked. It will reject talks and act tough just as it considers negotiations. Its defiant public message may not be the same as what it will countenance in private.

Iran will look for leverage in threatening to restart its nuclear program or disrupt the flow of oil and undermine regional stability to bargain with Mr. Trump for sanctions relief.

Maximum pressure has brought the United States close to war. If that is not what Mr. Trump wants, then he has to change tack. Pressure may get Iran to consider talking, but there has to be some give and take for negotiations to begin.

Mr. Trump has to convince Iran that he is serious. He needs the support of other signatories to the nuclear deal and world powers to convince Iran of his commitment to talks. He has to realize that unilateralism and maximum pressure have gone as far as they can.

If Mr. Trump seeks a deal, he has to invest in diplomacy. From here on the real of value maximum pressure lies in the price the United States can exact from Iran for easing it.

Vali R. Nasr is the dean of the Johns Hopkins School of Advanced International Studies.

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