Tensions between the United States and Iran have increased since President Donald Trump’s announcement last month that U.S. sanctions waivers would not be renewed, and that our goal was to “reduce Iran’s oil exports to zero.” It’s been an eventful few weeks, to say the least, with more developments undoubtedly to emerge in the near future.

Iran initially responded with veiled threats against U.S. interests in the region, and with threats to stop any other nation from exporting oil through the Strait of Hormuz if Iran’s oil exports were cut off by the sanctions. National Security Advisor John Bolton announced last week that the United States would deploy an aircraft carrier group and an Air Force bomber group to the region, citing specific threat reporting. On Wednesday, Iran threatened to begin withdrawing from certain parts of the 2015 nuclear deal, including ramping up enrichment work, if its European allies — sorry, we meant the United States’ notional European allies — did not take action to help Iran avoid the effects of sanctions. President Trump in turn announced new U.S. sanctions on Iran’s metal industry, which accounts for around 12% of Iran’s economy. Iran also declared all U.S. forces in the region “terrorists,” a move that is merely an angry tit-for-tat with no legal impact.

What might be the next steps in this dance? Iran’s response to similar tensions in the past has been to hold a large, highly publicized military exercise involving its naval and missile forces, with the explicit message that Iran can control the Strait of Hormuz. Both Iran’s regular Navy and its Islamic Revolutionary Guard Corps Navy have stopped and boarded merchant ships in the Strait of Hormuz, although none of those ships to date has been U.S.-flagged. Increased interference with merchant shipping, in particular oil tankers carrying Saudi or Kuwaiti crude oil, would be a simple way for Iran to exert leverage over the rest of the developed world’s economic safety.

Iranian-backed Shia militia groups in Iraq, which probably outnumber the Iraqi Army in manpower, are within eyeball range of U.S. forces every minute of every day, and would have ample opportunity to target those U.S. forces or the Iraqi forces we are training and supporting. And Iran can carry through on its threat to stop observing part or even all of the 2015 nuclear deal’s terms.

Or, Iran could agree to negotiate new terms to the nuclear deal. Those terms would have to include Iran’s ballistic missile development, its sponsorship of terrorism throughout the region, and the numerous unanswered questions about various Iranian nuclear facilities and past research on nuclear weapons. Iran has never allowed a detailed inspection of the Parchin complex, for example, and has literally dismantled and hauled away every brick and stone at other suspected facilities. It still has not provided a serious accounting of its pre-2003 work on nuclear triggers or warhead design. All of those issues must be addressed, and it is for that reason the United States has ramped up the pressure on Iran.

How long before that pressure changes Iran’s mind? Iran’s leaders are the true believers of the Islamic Revolution, and have suffered sanctions and deprivation since 1980. The Islamic Revolutionary Guard Corps functions as a virtual state within the state, and its senior leaders are the hardest of the hard-core. They have the ability to limit Iranian President Hassan Rouhani’s freedom of action if he was inclined to negotiate.

The Europeans have shown very little inclination to support efforts to limit Iran’s nuclear ambitions, preferring instead to trade with Iran and pretend Iran can be trusted. And China has several massive economic development deals with Iran, including a deal to modernize Iran’s oil infrastructure, in addition to being highly dependent on Iranian oil.

All of those factors add to the challenge of keeping the pressure on Iran until it produces the desired outcome. But that pressure must be maintained if we are to rectify the serious deficiencies in the Iran deal while avoiding war.