As the world focuses on the threat of nuclear war with North Korea, it’s useful to remember that good-faith negotiations can address even high-stakes international disputes. The Iran nuclear deal provides an example of what diplomacy can do—as well as the potential consequences if it is allowed to fail.

The Iran deal makes the world safer

The Joint Comprehensive Plan of Action, better known as the Iran nuclear deal, transformed a volatile and potentially violent situation into fertile grounds for lasting peace. The deal disrupted the trajectory toward war that the U.S. and Iran appeared to be on after years of threats and sanctions.

Intense negotiations that began in the early years of the Obama administration led to the final deal between the U.S., Iran, and five other nations in July 2015. This deal blocked every pathway for Iran to develop a nuclear weapon while reducing the risk of yet another U.S. war in the Middle East. Iran literally poured concrete in its heavy-water nuclear reactor as a result of the deal and opened itself up to the most rigorous inspections ever negotiated as required under the deal.

Over the past two years, Iran has complied with the deal, and the deal has helped to more fully integrate Iran in the international community, an important step in future nonproliferation and diplomatic efforts. Let the deal work

The truth is that, according to the UN nuclear watchdog (IAEA) reports, Iran is upholding its obligations, and two years into a 15-year deal is not enough time to know its full effects on Iran’s international engagement. The U.S. should not look for excuses to violate the deal’s terms. Both Secretary of Defense Jim Mattis and Chair of the Joint Chiefs of Staff Joseph Dunford have testified that remaining in the Iran deal is in the U.S. national security interest.

Yet last fall President Trump failed to certify Iran’s compliance with the deal. In January, he threatened to withdraw from the deal by mid-May unless it is radically altered, flagrantly rejecting the advice from diplomatic and nuclear experts around the world.

Preserving the Iran deal stops a slide toward war and guards against the possibility that Iran could acquire nuclear weapons. It also communicates to other nations—such as North Korea—that negotiating with the U.S. is not just a waste of time, and that we can uphold our end of the bargain.

Sustained diplomacy needed

Some of the deal’s critics point to other Iranian actions—such as ballistic missile tests and Iranian support for the Assad regime in Syria and Hezbollah in Lebanon—as reasons to leave the deal and impose new sanctions. Those critics believe the deal is weak because it doesn’t address these aspects of Iran’s behavior. The fact is the deal as negotiated addresses only nuclear issues, not conventional weapons. In order to address these other issues, we need more diplomacy with Iran, not less.

The U.S. should build on the success of the Iran deal to address Iran’s human rights violations and its role in the region. It is a misunderstanding of diplomacy to want to throw out a deal that is addressing one facet of disagreement because it doesn’t solve every problem that might arise between parties.

Diplomacy is about a practice of engagement over time. You don’t reach a single solution and stop. Instead of using these Iranian actions as an excuse to break the deal, these new issues should make the urgency of sustaining diplomacy all the greater, to provide a platform to address issues as they arise.

Destroying the Iran nuclear deal would be a big mistake, and we would face the consequences for generations. Your members of Congress need to know their constituents expect them to stand up for the deal and for diplomacy. We already have one nuclear crisis with North Korea. Let’s not manufacture another one.