As the U.S.-Israeli war on Iran drags on, questions about the campaign are multiplying. U.S. President Donald Trump’s rationale for going to war and the objectives he hoped to achieve were a moving target from the start. But with the fighting entering its third week, analysts are increasingly wondering how the war might end. Can the United States accept something short of regime change? And will the war have advanced U.S. interests in the region or set them back?

On FP Live this week, we put those and other questions to two analysts who agreed to square off in a debate. Matthew Kroenig and Trita Parsi have spent much of their careers writing about Iran—from different sides of the divide. Kroenig is an FP columnist and the senior director of the Atlantic Council’s Scowcroft Center for Strategy and Security. For years, he has advocated for U.S. strikes on Iran. Parsi is the executive vice president of the Quincy Institute for Responsible Statecraft. He also co-founded and formerly ran the National Iranian American Council. Parsi has called the war unnecessary and unjustified.

Subscribers can watch the full discussion on the video box atop this page or download the free FP Live podcast. What follows here is a lightly edited and condensed transcript.

Dan Ephron: Matthew, why is the war in Iran justified?

Matthew Kroenig: The definition of justified is whether something was done for a good or legitimate reason. And this was done for a good reason. Iran has posed one of the greatest threats to regional, U.S., and global security for many decades. It’s the world’s leading state sponsor of terrorism, according to the State Department. It has the largest ballistic missile program in the Middle East, that it’s used to attack its neighbors. It has had an illegal nuclear program that President [Barack] Obama called a defining national security challenge of our time. So it threatens global security.

Also, the Islamic Republic threatens its own people. It hangs homosexuals; it beats women to death for not wearing the headscarf properly; it just massacred thousands of its own citizens. So removing the Islamic Republic from the chessboard, or significantly weakening it for years, stands to greatly improve regional and global security and the lives of ordinary Iranians.

DE: Trita, you’ve called the war an “unnecessary war.” You’ve also said not a single death can be justified. Give us the case against.

Trita Parsi: It is utterly clear that this war is unjustified. I don’t see much of a debate on that specific point. The United States should only go to war when it is faced with an imminent threat and when all other options have been exhausted. In this case, no such evidence has been put forward. Donald Trump himself has been saying that his renowned military strategists, Jared Kushner and Steve Witkoff, believed that Iran would attack the United States. He did not say that the U.S. intelligence services had determined that an attack was imminent.

If you listen to Marco Rubio, it gets even worse. He says that the Israelis were about to attack Iran and, as a result, the fear was the Iranians would retaliate against the United States. If that is the case, it means that the Israelis were going to take action that endangered the United States. America should have told the Israelis not to do anything that puts American servicemen and women in harm’s way, instead of allowing the Israelis to decide when America goes to war.

The justifications and motivations for this war have been all over the place by the administration. In fact, they cannot stick to a story because they don’t have a story. It’s starting to look more and more like the 2003 war, but at least the George W. Bush administration put some effort into the lies that it told the American people at the time.

DE: Trita, in the past two weeks, Iran has attacked almost all of its neighbors, including some of its own allies. It has also attacked shipping lanes. So how can you make the case that Iran is not a threat to the region?

TP: The Iranians have the capacity to strike these states, of course, but it’s only done so when the United States has struck Iran, as was the case in June of last year and as is the case right now. What the Iranians are doing to these states is extremely problematic, particularly for the states that have played such a critical role in trying to avoid this war. But to say that just because they have the capacity to do so, they are automatically a threat essentially means that the United States would only be happy if Iran has no military capabilities at all. And that is completely unachievable. If the United States is concerned about the safety of these states, it should have taken that into account before starting this war of choice.

DE: Matthew, the administration calls Iran an imminent threat—but its proxies have been decimated, and its military was significantly set back last June. What evidence have you seen?

MK: First, I think Iran has posed an imminent threat to the United States since 1979. Iran and its terrorist and proxy groups have killed Americans in Beirut, killed Americans in Iraq and Afghanistan, plotted to blow up Georgetown restaurant Cafe Milano, have active plots to try to kill former U.S. officials, including Robert O’Brien, Mike Pompeo, Mark Esper.

Really, the question is, why did the United States wait so long? The United States thought it needed to tolerate these threats for many decades. And finally, we have a president who’s saying, “No more. We’re going to finally address these imminent threats.”

DE: I want to ask about the legitimacy of the war. The administration didn’t consult Congress before striking Iran. It didn’t go to the U.N. Security Council for a resolution. It didn’t even make the case publicly for war with Americans. If the case was so strong, why not air it out?

MK: Some of the key principles of the rules-based international order that the United States and its allies established 80 years ago are not to threaten your neighbors, not sponsor terrorism, not build nuclear weapons, have free market economies, and establish democracy at home. Iran has been violating all of these rules and principles for decades. And so if you want a functioning rules-based international system, what do you do with a state like this? It falls on a country like the United States to enforce the rules. There have to be consequences for a country like this that continually violates the rules

DE: Trita, do you want to respond to Matthew?

TP: Trump has never even used the term “rules-based order.” And one of the most important rules of the international order is that you don’t attack other countries. And you certainly don’t do it without any imminent threat. And also, you have to go through the Security Council. To say that this war is aimed at upholding international law is frankly preposterous.

At the end of the day, the United States and Iran have been in some form of a conflict with each other politically, diplomatically—that does not justify military action. Because if that is the standard, the United States would be in conflict all the time because we constantly have these different types of diplomatic problems. The bar for going to war is much higher than to say that we’ve had problems with the country for 47 years.

MK: I disagree that this is normal diplomatic differences that the United States has with many countries. The Islamic Republic of Iran is one of the most evil countries on Earth. It’s working with Russia, China, and North Korea to undermine global order.

The U.N. Security Council was mentioned. But it gives Russia and China, two of the countries trying to tear down the order, a veto. So the U.N. Security Council essentially never worked.

This technical legal debate is missing the forest for the trees. This is one of the greatest threats to global security. So whether they went to an international body gets in the weeds and is not that relevant.

TP: I find it astounding to say, on the one hand, that this is a war to uphold the rules-based international order and then say that the Security Council doesn’t matter and it’s never worked.

Bottom line is, I’ve not heard Matthew put up any evidence that there was an imminent threat. That is the standard for the United States to go to war.

MK: Again, I think we’re focusing on the wrong issues with imminence. The real problem here is that Iran has been a threat to its own people and to the world for 46 years. And so, to turn it back to Trita: What is your solution? How do we stop the Islamic Republic from abusing the human rights of its own people? How do we stop it from sponsoring terrorist attacks all over the world? From trying to kill my friends here in Washington? How do we stop it from building this illegal nuclear and missile program? Trump has an answer. You don’t.

TP: There actually was a solution. The JCPOA [Joint Comprehensive Plan of Action] was working. The nuclear threat had been taken off the table as a result, and we had the diplomatic opening to be able to start addressing other issues, from their use of various [proxy] groups in the region to their domestic situation. We had a pathway that was far more effective than blowing up the entire region, as is now happening. So when you say that I don’t have an answer and Trump does, you are saying that this war, which has already turned into a debacle, should actually perform as an answer to all of that.

DE: I want to turn now to how the war is going. Trita, Iran has attacked commercial targets, civilian targets, and has effectively shut down oil exports from the region. If Iran’s goal is to counter the American narrative that it is a menace to the world, how do these attacks serve that purpose?

TP: The Iranian aim here is not to counter the United States’ accusations against Iran. The Iranians are trying to make this war as costly as possible for the United States and for everyone else so that everyone concludes that this war was a mistake. It should not have been started. And as a result, the United States and Israel will not restart the war in another seven or eight months. Unfortunately, this goal has led them to do these attacks, which I absolutely agree are completely illegitimate.

DE: Matthew, if the fighting ends today with the regime intact, Iran can plausibly argue that it has won the war. The regime was targeted by two of the most powerful militaries in the world and survived—and not only survived but actually created a new form of deterrence for future attacks with its strategy in the Gulf. How would you counter that argument?

MK: From the beginning, the Trump administration has said its objectives in the war are to degrade Iran’s nuclear, missile, drone, and navy capabilities. It is succeeding at that; the military has said it’s ahead of schedule. Trump has said it will take a couple more weeks to go after drone and missile manufacturing capabilities. This will significantly weaken Iran’s ability to terrorize the region, at least for years, maybe a decade.

In terms of governance, there is still a chance that the Iranian regime falls. It would be terrific if there is a better government in Iran that respects human rights and cooperates internationally. Another scenario is the Venezuela scenario. I don’t think the current supreme leader is going to last for long. So, at some point, do we get down to somebody who is willing to play ball in order to survive?

DE: Trita, could the regime hang on to power and emerge intact after the war?

TP: We have seen quite clearly that this theocracy in Iran is far more resilient than Washington assumed. It is actually benefiting from the war in some ways. Their base, which isn’t more than 15 or 20 percent of the population, has been energized. U.S. and Israeli intelligence are picking up on a wave of nationalism spreading throughout the country. As much as the overwhelming majority of Iranians would like to see a very different government in Iran, they are not seeing this effort actually bringing that about. They’re seeing this effort destroying the country, bombing desalination plants and refineries, making it impossible for people to even breathe in the capital. They’re increasingly seeing it as a war against the country.

DE: Trita, how might the Gulf countries attacked by Iran—including Qatar and Saudi Arabia—reconsider their relationship with the United States as a result of the war?

TP: First of all, they will also reconsider their relationship with Iran. They are absolutely infuriated with what Iran is doing. Bahrain, as the representative in the GCC [Gulf Cooperation Council], led the resolution [condemning Iran’s attacks] that was adopted by the Security Council.

But there are also implications for their approach toward the United States. There are 19 or so American bases in the region, many of them in the GCC states, as a way of deterring Iran. Instead, now you have a scenario in which the United States itself actually started that war. And once the war was started, these bases did not end up protecting these countries but instead became the targets.

In the short run, I don’t think much will change. But over the longer run, there will be a lot of rethinking in the region about whether they should put all of their eggs in the American security basket and whether the presence of these bases adds to or reduces their security.

DE: Matthew, same question. Will the United States pay a price in terms of its alliances with Gulf countries?

MK: What’s been most striking to me is that diplomacy seems to be breaking the United States’ way. People’s initial anger with Israel and the United States shifted, after a couple days, to Iran. We have seen the Gulf states condemn Iran’s behavior. European and Indo-Pacific allies are siding with the United States, and the British changed their minds to allow the United States to use one of their bases. If the war either significantly degrades Iran’s ability to threaten the region or leads to a better government in Iran, the region, the world, and historians will thank Trump.

DE: The deeper the United States gets into this war, the more there is celebration in China and Russia that the United States is getting sucked into a quagmire. Does that worry you?

MK: In the short term, this does reduce America’s capacity to address threats in other theaters. We’re using a lot of munitions; there is a readiness drain as maintenance and training aren’t happening.

But over the medium to long term, this greatly strengthens the United States’ hand and puts Russia and China in a more vulnerable position. First, it removes one of the “axis of aggressors” from the chessboard. So their alliances are getting weaker and smaller.

Secondly, these constant, nagging threats posed by Iran have prevented the United States from pivoting to Asia, as it has been wanting to do for some time. Decisively addressing them could allow the United States to finally prioritize the threat from China in the Indo-Pacific.

DE: Trita, how do you respond to that question? How is this war affecting U.S. interests in other parts of the world?

TP: I’m astonished because this sounds almost verbatim how the Iraq War was justified—that this would just usher in an era of euphoria and everything will be stable. We have seen in Afghanistan, Libya, Syria, and Iraq that that is absolutely not the case.

The long-term effect for the United States, I fear, is that many countries—though they may not say so publicly—increasingly see the United States as a destabilizing actor because of these wars of choice. On the other hand, China is not seen as a country willfully starting wars that leave these regions with unpredictable consequences while washing its hands of it.

So I worry that American credibility as an upholder of security and of international law is being undermined with these wars of choice. We’ve seen the consequences for American people with these debacles, when we go to war with no justifiable basis, with the Iraq War. I am very fearful of what this will do for the United States and the American people in the next 10 years if it goes in the same direction.

DE: Matthew, unless the situation changes, it’s hard to see how this war would serve the interests of Iranians who want to see more freedom and democracy in their country. If the regime survives, it will likely crush dissents even more harshly than it did just a month ago. That might end up being one of the legacies of this war.

MK: Trump drew a red line and told the Iranian regime that if they killed protesters, there would be hell to pay. They killed thousands of their own citizens anyway, and we’re seeing now that Trump meant it. So a future government in Iran is going to think twice about massacring its citizens, knowing that this could be the consequence.

Contrary to what Trita was saying, this improves American credibility. With past administrations, there was a question of whether the United States had the stomach to use military force. Now we see that it does. And since everybody seems so focused on international law, we haven’t talked about the “responsibility to protect” principle, which says that governments have a responsibility to protect their own citizens and if they do not, then outside powers have a responsibility to intervene. So, by reinforcing that red line, things could get better for the Iranian people even if the Islamic Republic manages to hang on to power.

DE: Trita, I’m going to give you the last word here.

TP: We’re seeing very clearly that this is not going in the direction that the administration wanted. The idea that this is strengthening American credibility? No one serious doubted that the United States was willing to use military force. What people doubt is America’s ability to work for stability, to respect international law and not wreck the entire international system.

We’re constantly being told that the only credibility that matters is whether we use military force or not. This is turning the United States into a country whose only contribution is its ability to blow things up. That is not the vision of America that the vast majority of Americans want.