Joseph I. Lieberman, a former U.S. senator from Connecticut, is chairman of United Against Nuclear Iran. Mark D. Wallace, a former U.S. ambassador to the United Nations for management and reform, is chief executive of United Against Nuclear Iran.

Like President-elect Donald Trump, we vigorously opposed the Iran nuclear agreement, so we sympathize with his promise to “dismantle” it. But we hope that he and his administration will first try to aggressively enforce and then renegotiate the deal beyond the confines of the nuclear issue to make it better for us and the world.

Before such renegotiations begin, the Trump administration could strengthen its hand by closely consulting with our allies in Iran’s neighborhood — Israel and the Arab states. They were missing from the group that developed and consented to the Joint Comprehensive Plan of Action (JCPOA), as the agreement is formally known. That was wrong, for two main reasons: because the Arab states and Israel are our allies and the Iranians are not, and because the countries in the region have the greatest equities at stake and should have a significant voice in the outcome.

To date, the Iranian regime has made clear it has no intent to honor the spirit or letter of the JCPOA. Iran’s pattern of reckless behavior has accelerated over the past year. Its anti-American, anti-Israel and anti-Arab rhetoric has grown stronger, and its actions have matched its rhetoric. Last month, 11 Arab states publicly accused Iran before the United Nations of meddling in their internal affairs. In June, the State Department again designated Iran the world’s leading state sponsor of terrorism.

President Obama said the Iran deal is an example of the gap between rhetoric and reality during a news conference Monday, Nov. 14. (The Washington Post)

The American people see clearly what is happening. According to a recent survey by United Against Nuclear Iran, a large majority of American registered voters view Iran as the greatest state threat facing the United States — ahead of North Korea, Russia and China. Only the Islamic State and al-Qaeda are deemed bigger threats.

With U.S. leadership, the new coalition could address the policy omissions in the JCPOA by, for example, securing an agreement with Iran to verifiably curb its regional aggression, state sponsorship of terrorism and domestic repression of human rights. In exchange, Iran could be given broad-based sanctions relief and even normalization of relations.

However, if Iran refuses, the United States and our allies will have great leverage to hold Tehran accountable under the existing accord. Iran has already twice exceeded its allotted limit for heavy water; it has test-fired multiple ballistic missiles, in defiance of U.N. Resolution 2231, which endorses the nuclear deal; and, according to German intelligence estimates, Iran has continued its “illegal proliferation-sensitive procurement activities” at a “quantitatively high level.” The United States and its partners have closely adhered to the letter of the JCPOA; they should demand that Iran do the same.

The Trump administration can also designate the entire Islamic Revolutionary Guard Corps (IRGC) as a foreign terrorist organization. To date, only its extraterritorial Quds Force has been labeled as such by the Treasury Department. If done correctly, such a move could freeze foreign investment in Iran because of the IRGC’s pervasiveness in the Iranian economy through front companies.

Trump can also support legislation in Congress punishing sectors of the Iranian economy that support Iran’s ballistic missile program, and he can propose measures to curb Iranian access to U.S. dollars.

To persuade Iran to abide by both the letter and spirit of the JCPOA, as Dennis Ross and retired Army Gen. David H. Petraeus have argued, strengthening deterrence will be key. Setting forth a “blunter statement on the consequences” of continued Iranian intransigence — even in an authorization for the use of military force in the most dire crisis — might change Ayatollah Ali Khamenei’s calculations.

If Iran does not change course, the president-elect should make clear he is prepared to impose a new round of comprehensive secondary sanctions against Iran — and then to walk away, with cause, from the JCPOA. Then it will be time, as the president-elect has said, to tear up this agreement.

Such a step-by-step strategy will make clear that the United States is willing to work with Iran but that there will be consequences for the Iranians if no diplomatic solution is reached. At its best, such an approach can be transformational. At the least, it will rewrite the current nuclear deal, relegating to history a period in which the great powers legitimized Iran’s rogue nuclear program without asking the regime to change its radical, terrorist, repressive and expansionist ways.