Rejection of the Iranian nuclear deal would make diplomatic solution in North Korea impossible, further exacerbating that crisis
The United States has few options for dealing with the North Korean nuclear challenge, and no good ones. A pre-emptive strike risks an unspeakable catastrophe. Sanctions have not worked, and tightening them further is no more likely to. Diplomatic talks will be difficult for the United States because an agreement would involve a compromise that would allow North Korea to keep its nuclear weapons. Nonetheless, if the goal is to prevent Pyongyang from developing an accurate nuclear-tipped ICBM, then negotiating with Pyongyang may well be the only way to try to defuse a looming crisis.
Even under current conditions, such talks would be fraught, the odds tilted against success. But if the U.S. thrusts aside the nuclear deal with Iran—and uses contrived evidence to do so—the message to North Korea and others will be that America’s word is disposable and the U.S. cannot be trusted to honor its commitments. This would deal a possibly fatal blow to any chance of a diplomatic effort to, if not halt or reverse, at a minimum slow down North Korea’s nuclear and ballistic missile programs.
Indeed, walking away from the Iran deal, or contriving circumstances that force Iran to do so, would not only open up a now dormant nuclear crisis with Tehran, it would also close down perhaps the only option that might prevent a far more dangerous crisis with North Korea.
If the U.S. congress rejects the nuclear deal with Iran, it will have multiple negative reprecussions for U.S. interests and security. The most likely impact of U.S. rejection of the deal will be a gradual collapse of the sanctions regime as our partners have no interest in reopening negotiations with Iran and are already starting to renew trade relations. Additionally, rejection of the deal will damage U.S. credibility as a global leader and its diplomatic capital for many years as the U.S. was critical in forming the consensus for the deal in the first place.