In May 2018, the Trump administration unilaterally withdrew from the Joint Comprehensive Plan of Action (JCPOA), which was designed to prevent Iran from acquiring a nuclear weapon and had been agreed on after 12 years of exhaustive negotiations.

The US began to impose new economic and political sanctions, targeting not just various sectors of the Iranian economy, but the state’s most influential entities and actors. The imposition of these sanctions has virtually killed off the possibility of diplomatic efforts to resolve the crisis and will have political consequences for not just Iran and the US, but the whole region. The current situation is extremely fraught, with Iran responding to aggressive actions by increasing its level of uranium enrichment.

The reemergence of hostility between Iran and the US – after a period of detente under Barack Obama – is one of the most urgent challenges to peace and security in the Middle East. And yet Trump’s belligerent policies have all but blocked conventional channels of diplomacy.

For one thing, cooperation requires dialogue between the countries’ respective military establishments in the region. US Central Command (Centcom) and Iran’s revolutionary guard corps’ Quds force are both responsible for their countries’ extraterritorial operations. The IRGC’s designation as a terrorist organisation – and Iran’s reciprocation against Centcom – has ended the possibility of negotiation between these two extremely influential state entities.

Next, in an unprecedentedly aggressive action, the Trump administration has imposed sanctions on Iran’s ultimate source of authority according to its constitution, namely the supreme leader Ayatollah Ali Khamenei. Just as in the US the president has the authority to determine the general trajectory of foreign policy, the supreme leader in Iran is the one who sets the foreign policy of that country. Let’s not forget it was the supreme leader who allowed direct negotiation with the US over the nuclear issue in the first place. By sanctioning Ali Khamenei, Trump has effectively killed off any chance of diplomatic rapprochement so long as he is in office. And it is not only the political leadership of Ali Khamenei that is relevant here; he is also a religious scholar with millions of Shia Muslim followers – not just in Iran, but Iraq, Pakistan, Afghanistan, India, Bahrain and elsewhere.

In addition, last week, the treasury secretary Steven Mnuchin said the Trump administration was looking to levy penalties against Iran’s foreign minister, Javad Zarif, who trained in the US and is one of the most distinguished career diplomats in Iran’s recent history. Zarif has been compared to the popular prime minister Mohammad Mossadegh, who nationalised Iran’s oil industry and was deposed in 1953 in a coup organised by Britain and the US. Sanctioning Zarif is a mistake if the US ever wants to reengage with Iran, because he is in charge of the diplomatic channels that would be necessary to resolve this crisis. As Wendy Sherman, who led the US negotiating team in the talks that led to the 2015 accord, put it: “I can’t think of anything that makes less sense than sanctioning a key person who might actually be helpful if there is ever a dialogue with the US.”

Donald Trump with a signed executive order to increase sanctions on Iran: ‘Deploying phony, rhetorical offers of talks at the same time as imposing devastating sanctions will not make Iran yield.’ Photograph: Alex Brandon/AP

The Iran nuclear deal is the most comprehensive agreement in the history of non-proliferation. As part of it, Iran accepted the most intrusive transparency measures and stringent limits on a nuclear programme ever demanded of a non-proliferation treaty member. What is more, the International Atomic Energy Agency (IAEA) recently judged that Iran was in full compliance with the terms and conditions of the JCPOA.

But where Iran has kept its end of the bargain, it has been rewarded with sanctions and additional pressure, and the benefits Iran was supposed to receive have been suddenly snatched away. The Trump administration made a decision to undermine the diplomatic legacy of Obama, but it may not have fully understood that in doing so it would also be obliterating any possibility of brokering its own diplomatic solution.

Trump has consistently offered to talk to Iranian officials, but his actions have been by far the most belligerent since the 1979 revolution. Deploying these phony, rhetorical offers of talks at the same time as imposing devastating sanctions is not a strategy that will make Iran yield.

Iran warned world powers in advance that if the other parties failed to meet their commitments, it would begin to reduce its obligations under the JCPOA. As a first step, over the past few days, it exceeded the 300kg limit on its uranium stockpiles. It has now also announced it will enrich uranium above the 3.67% limit specified by the deal. In addition, the Iranian president, Hassan Rouhani, has told his cabinet that the Arak reactor will be restored to its original design which, it was claimed, would be able to produce plutonium. It is crucial to note that this is the first time Iran has contravened the JCPOA. Ever since the Trump administration withdrew last year, Iran has been patiently waiting for the other parties involved in the nuclear agreement to honour their commitments, but the only outcome was the intensifying of pressures and sanctions. Iran cannot be expected to fully comply with the deal when others are failing to meet their obligations.

Trump single-handedly undid 12 years of intensive negotiations between Iran and world powers by withdrawing from the nuclear deal. He chose the dangerous path of hostile policies and actions and has increased the likelihood of yet another disastrous conflict in the Middle East. He does appear to recognise that a military confrontation with Iran would be catastrophic in every possible way. But he should also realise the fact that Iran will never give in to bullying.

If Trump genuinely wants to resolve this unnecessary, self-imposed crisis, he needs to make a swift strategic turnaround, one that would allow both countries to save face. Only then would credible diplomacy become possible once more.

• Hossein Mousavian is a former member of Iran’s nuclear negotiating team. He is currently a policy specialist at the Program on Science and Global Security, Princeton University