This year has not started well for Iran. In a single US drone strike, Iran lost two of its most powerful terrorist operatives: IRGC-Quds Force commander Qasem Soleimani and Kataib Hezbollah chief Abu Mahdi al-Muhandis. Iran then tragically downed a civilian airliner over Tehran airspace, killing everyone on board, and lied about it for several days. The Iranian economy is in crisis and ordinary Iranians have courageously taken to the streets demanding that Supreme Leader Ayatollah Ali Khamenei step down. Yet, rather than acknowledge that the continuation of his policies will bring about more isolation and economic ruin, Khamenei is doubling down, ordering loyalists to go on the offensive. Twice this month, for instance, Foreign Minister Javad Zarif directly threatened United Against Nuclear Iran (UANI), the US-based advocacy group that we lead. In one set of remarks made to reporters, Zarif said, “One of the organizations active in the area of reinforcing US economic terrorism against Iran is United Against Nuclear Iran, whose whole name from beginning to end is a pack of lies.”Zarif’s remarks are an obvious effort to distract the Iranian people from the regime’s brutality and corruption. It also confirms that the US-led “maximum pressure” campaign is succeeding.Such threats will inspire those of us who support that campaign to redouble our efforts to hold Tehran accountable for its actions, and to stop businesses around the world from engaging with the regime and its terrorist agents. Our goal is to convince Iran to end its malign behavior and behave like a responsible member of the community of nations, or sacrifice the viability of its economy and watch its people continue to suffer. History has shown that when forced to make a choice, the ayatollah has demonstrated a willingness to negotiate, as regime survival is his primary concern.The Trump administration has initiated the maximum pressure campaign against Iran to do just that. It’s working well, but there are other actions that it can take – with or without international partners – to force Khamenei to the negotiating table.The president can reinforce the economic component of the maximum pressure campaign by making greater use of his authorities for addressing human rights abuses and corruption in Iran; broaden the scope of activities constituting “significant support” to Iran’s shipping sector; designate additional Iran-backed Shi’ite militias as foreign terrorist organizations; and use its status as a “Joint Comprehensive Plan of Action participant” under UN Security Council Resolution 2231 to trigger the snapback of international sanctions.The president can also marshal our allies in Europe to sanction Hezbollah as a terrorist organization; end the terrorist Mahan Airline’s ability to operate anywhere on the continent; and push the Financial Action Task Force to fully reimpose countermeasures on Iran’s financial system when it meets for its plenary later this month.The Islamic Republic of Iran’s bad year might get worse before it gets better. Those in power are to blame. They have to change their behavior or reap the consequences of their current unsustainable path, which has led to a faltering economy and a restive population. For all those who look at decades of lies, corruption, death and terrorism, it’s time to say baseh digeh – “that’s enough.”At his State of the Union address, President Trump spoke directly to the Iranian regime’s leaders. He demanded that they abandon their malign behavior and start working for the good of the Iranian people. And he reminded Tehran that as quickly as the maximum pressure campaign laid waste to the Iranian economy, the US can help rebuild it, if only Iran will stop developing nuclear weapons and end its support of terrorism.“We are here,” Trump said. “Let’s see which road they choose. It is totally up to them.”Only Khamenei and his regime can make the big course corrections that are rightfully demanded and entirely necessary or, ultimately, the Iranian people will step in. We can help them make that decision so the world becomes safer faster.Joseph I. Lieberman is a former Democratic US senator from Connecticut, and the 2000 Democratic nominee for vice president of the United States. He is chairman of United Against Nuclear Iran. Mark D. Wallace, a former US ambassador to the United Nations for management and reform, is UANI’s chief executive.