US President Donald Trump has decided not to certify that Iran is in compliance with the terms of the Joint Comprehensive Plan of Action (JCPOA), the agreement constraining Iran’s nuclear-weapons program. In effect, Trump has challenged the US Congress to do what is normally the executive branch’s responsibility: create foreign policy.

What that policy will be remains an open question. While Congress is already preparing sanctions, these will not, on their own, comprise a comprehensive Iran strategy. Instead, the US and Iran will need to negotiate directly on a range of non-nuclear issues.

As it stands, few assert that Iran is actually failing to comply with its obligations under the JCPOA. Even US Secretary of State Rex Tillerson, who has made no secret of his disdain for Iran, complains only that Iranian leaders are violating the ‘spirit’ of the deal. But the JCPOA is clearly—and deliberately—focused on curbing Iran’s nuclear-weapons development, not its missile programs, regional ambitions or animus towards Israel.

The Trump administration also takes issue with the time limits on the JCPOA, with some provisions—such as strict limits on research and development of advanced centrifuges—in effect for just 10 years. Trump’s denunciations of the deal have fuelled debate over the appropriateness of the time limits, though such discussions often fail to recognise that Iran agreed to adhere to International Atomic Energy Agency standards, including its advanced inspection protocols.

In any case, the key to preventing recidivism after the JCPOA sunset provisions expire will be to move Iran towards good-neighbour policies, and to ensure that its economic interests supersede its ambition to become a regional hegemon. That is where bilateral negotiations come in.

One reason why the JCPOA did not cover non-nuclear issues is that several other partners and allies—namely, China, France, Germany, Russia, the United Kingdom and the European Union—were involved, and each had its own perspective and objectives. Regional powers with ringside seats to the talks, such as Saudi Arabia, also had plenty to say.

Reconciling these actors’ conflicting interests and demands concerning the full range of relevant issues would have been next to impossible. Bilateral negotiations between the US and Iran, however, might allow the US to make progress on the issues that are important to it—and, equally significant, to understand modern Iran better.

Such negotiations would likely start with a lengthy discussion of the two sides’ conflicting interpretations of the history of their relationship—in other words, each country’s grievances with the other. For Iran, such grievances include US support for the 1953 coup in Iran, and America’s subsequent ties to the Shah and his brutal secret police, the Savak.

The US, for its part, would probably raise the 1979 abduction of US embassy staff by Iran’s fledgling Islamic revolutionary regime, and, more recently, its targeting of American troops using Shia militia groups in southern Iraq. These discussions should include detailed questions and specific answers. Working groups might be established to try to create a common narrative.

The negotiations would also need to cover contemporary issues, including a tour d’horizon of current hotspots. What is Iran doing in Yemen, Lebanon, Iraq, and especially Syria? How does it define its interests in these countries? Does it actually see itself, as many Sunni Arabs assert, as a protector of Shia Arabs?

In Iraq, the US invested heavily in toppling Saddam Hussein’s regime and then in supporting a political process that has produced a Shia-led government—a positive outcome, from Iran’s perspective. The key question, then, is why Iran continues to support militia groups that have often undermined Iraq’s government.

As for Syria, Iran moved quickly to support President Bashar al-Assad’s government. Iran’s backing of an administration dominated by the minority Alawites (a Shia sect) has clearly unnerved Sunni Arab states, especially Saudi Arabia, which regards with great concern this ‘Shia crescent’ just across its northern frontier. Iran cannot really expect the Saudis to be indifferent to such a change in their geostrategic position.

But Iran is not the only actor that must explain its Syria strategy. The US, too, has so far pursued policies that, to put it mildly, have not always had a self-evident rationale. Now is the time for the US to put its cards on the table. Does it seek regime change, or would it settle for policy changes by whatever government Syrians eventually choose?

And what about Israel? During his presidency from 2005 to 2013, Iran’s Mahmoud Ahmadinejad inflamed world opinion by repeatedly questioning whether the Holocaust happened. Does this kind of ignorance and contempt for the Jewish people persist among Iran’s current leadership, colouring their approach to Israel?

The final vital issue that must be addressed in any bilateral talks between the US and Iran is the latter’s military activity and, in particular, its missile programs. Iran frequently alludes to its right to maintain a modern military, with advanced missiles, though unlike, say, North Korea, it stops short of claiming a right to nuclear weapons. To determine the appropriate role and capabilities of Iran’s military, direct talks between the US and Iranian militaries, like those the US has pursued with China, might be in order.

The US cannot continue to base its policy towards Iran—a huge country with a population of over 80 million, a growing economy, and strong regional influence—on sanctions and vitriol. Likewise, Iran needs to retire poisonous slogans like ‘Death to America’ and instead work with the US to advance its own interests and aspirations. Perhaps the mountain of mistrust will turn out to be too high for the two countries to scale. But getting to the other side is worth a try.