In the case of international agreements, your word is your bond. For sovereign nations to agree on consequential issues, they must each be assured that the duration of their cooperation will persist through changes in partisan leadership. This seriousness doesn’t apply to all aspects of politics, but is does apply to at least one if nothing else: nuclear weapons.

The Iran deal, or the Joint Comprehensive Plan of Action (JCPOA), is one of the more consequential agreements. Under it, the European Union and the countries on the United Nations Security Council agreed to unfreeze huge assets held by Iran in overseas banks and lift economic sanctions. In return, Iran would halt its uranium enrichment efforts and submit to third-party inspection of its nuclear program.

President Donald Trump’s decision not to recertify the deal, as must be done every 90 days, is a major blow to American credibility. It isolates the United States from its allies, all of who support the deal’s continuation. Iran will also be less likely to negotiate with the United States in the future in the case that, as Iranian Foreign Minister Mohammad Javad Zarif points out, they believe “the duration of any commitment from now on, with any U.S. administration, will be the remainder of the term of that president.”

Even more important than the loss of international respect, the decision not to recertify this deal is dangerous. The world is a safer place when there are fewer nuclear weapons. Iran will have little reason to honor its pledge to halt its pursuit of nuclear arms. Additionally, Trump’s decision will embolden Iranian hardliners, who were against the deal when it was signed and have become a powerful force in Iranian politics.

In addition to being dangerous, the decision not to recertify is stupid. Trump’s key reasons for his opposition to the deal are that it is unfair and that Iran is not complying with its terms. However, the International Atomic Energy Agency, whose function is to monitor Iran’s compliance, has concluded that they are indeed honoring the terms laid out. In reaction to Trump’s announcement, leaders from every other major country that signed the JCPOA, such as Angela Merkel of Germany and Emmanuel Macron of France, have urged Iran that they will continue to honor their word.

The argument that the deal was “unfair” is also ludicrous. The Iranian regime received money it technically owned in order to pay for domestic needs and reviving its currency, and in return the world has one less nuclear power to worry about.

Now that Trump has failed to recertify, it is up to Congress to decide what to do. They could do anything from recertifying the deal to imposing economic sanctions, including killing the deal by forcing a renegotiation.

Congress must act in accordance with America’s best interest and recertify the deal. Bowing to political pressure by failing to do so would cement the loss of our international credibility and authority. It would embolden hardliners who see a nuclear weapon as a means of establishing regional dominance. Finally, it would also increase the amount of nuclear weapons in the world without working towards a more peaceful international arena.