Under President Barack Obama, whose foreign-policy legacy was anchored to the nuclear deal, the promise of deferring (not preventing) Iran’s nuclear ambitions superseded all else. As a result, the fear of Iran walking away paralyzed Washington and prevented the Obama White House from making even reasonable demands of Tehran. The credible threat of a U.S. response to Iranian aggression was effectively off the table. So was the imposition of meaningful new sanctions, for that matter.

The coming decertification announcement provides an opportunity to break this paralysis. Trump is effectively telling Tehran that he sets the terms for the nuclear deal because he is not tethered to its success the way Obama was. The administration will then have a chance to chart its own Iran policy. As the 60-day INARA review period plays out, Trump can regain U.S. leverage, establish new red lines on Iranian behavior, and (unlike his predecessor) actually enforce them. If he does it right, he can do all of this without exiting the deal.

In response to decertification, Iran’s leadership will undoubtedly threaten to walk away from the table. But it’s not that simple. There are benefits the Iranians have yet to reap from the deal—beyond the more than $100 billion in released oil funds—ranging from increased foreign investment to greater integration with the global economy after years of economic isolation. In other words, Iran can still cash in considerably, but not if it balks at Trump’s calls to fix the deal.

The Europeans, Russians, and Chinese, are also reluctant to go along with Trump’s certification gambit. Some are already howling with disapproval. But some are already voicing their willingness to work with the White House. As the primary investors in Iran’s recent economic rebound, they have little choice but to try to resolve American concerns.

Of course, even the Chinese, Russians, and Europeans understand that they have a daunting task ahead of them. Iran is on a collision course with the West, one that has little to do with the nuclear file. Rather, it is about what the nuclear deal negotiators chose to ignore: Iran’s aggression across the Middle East.

Iran has harassed American ships in the Persian Gulf, held American sailors at gunpoint, bankrolled the murderous Assad regime in Syria, supported the Houthi rebels in Yemen, and furnished the majority of Hezbollah’s operating budget. And those are just a few of the highlights.

Tehran’s broader efforts to dominate the Middle East are also intensifying. From the deployment of its Revolutionary Guard Corps to far-flung corners of the region to the conscripting of Shiite irregular proxies to fight or hold territory in Syria and Iraq, Iran’s footprint continues to grow.

For American policymakers, Iran’s bid for regional hegemony is just as troubling as its nuclear ambitions. Together, they represent a dual Iranian strategy that cannot be separated, despite the P5+1’s efforts to do so back in 2015. This is why Trump should build on his decertification announcement with the rollout of a new Iran policy that actively counters these activities.