Five Arab nations—including Egypt, Saudi Arabia, and Bahrain—severed all diplomatic ties with Qatar on Monday, exposing deep rifts between the Middle Eastern nations. Qatar, in turn, expressed “deep regret,” saying that the country has been “subjected to a campaign of lies.”

The move to isolate the country follows an alleged hack of the state-run Qatar News Agency, which resulted in the release of a purportedly fake report quoting the emir as praising Iran and speculating that President Trump might not remain in power for long.

Analysts view the division as the biggest diplomatic crisis between regional neighbors since the Gulf War of the early ’90s. As relationship dynamics in the Middle East shift, we asked professor Denis Sullivan, co-director of the Middle East Center at Northeastern, to explain the geopolitical impact of isolating Qatar and how the U.S. might respond.

The five Arab countries that severed ties with Qatar cite Qatar’s “support for ISIS, Al-Qaeda, and the Muslim Brotherhood” as one of the reasons for isolating the nation. How might this move impact the future and stability of the Gulf Cooperation Council, an intergovernmental political and economic union consisting of all the Persian Gulf’s Arab states except for Iraq?

The GCC was formed in 1981 at the start of the Iran-Iraq war, with six member states: Saudi Arabia, Qatar, United Arab Emirates, Kuwait, Bahrain, and Oman. While the impetus was a shared fear of being swept up in the war between Iran and Iraq, the GCC had its best success, relatively speaking, on economic cooperation matters rather than in security or military cooperation. The current diplomatic, economic, and political isolation of Qatar may indeed kill the GCC, or at a minimum severely wound it. It certainly poisons the well for any regional or GCC cooperation anytime soon—especially in Syria, where Qatar, Saudi Arabia, and Iran all have supported different sides or factions within the Syrian civil war.

The Arab countries also announced that they would cut air, sea, and land links with Qatar, marking the biggest regional rift in decades. What does this say about the future of Middle Eastern alliances going forward?

I’m in Amman, Jordan, right now, and on Wednesday Jordan also joined the Saudi side—sort of—by downgrading its diplomatic relations with Qatar. Jordan, like Oman and sometimes Kuwait, does not like to take sides in such inter-Arab conflicts but now it must follow “Baba Saudi,” or “Father Saudi,” a major economic partner and patron. Still, Jordan will suffer by joining the growing isolation of Qatar for it also means cutting its own economic hide, since Qatar is a major employer of Jordanian expat labor; this could mean 50,000 or so Jordanian workers either stranded in Qatar without work or suddenly expelled from Qatar, thus further inflaming the crisis. And what is true for Jordan’s expat labor is at least five times worse for Egypt, which has over 250,000 of its nationals working in Qatar. So, Middle Eastern economic and political and military alliances? Going down the drain fast and furious each day this crisis continues.

Many analysts believe that the reason for this move stems from Qatar’s friendly relationship with Iran, with the “nail in the coffin” coming from the purportedly fake Qatar News Agency report. What factors, in your opinion, played the biggest role in catalyzing this crisis?

This report is now largely debunked. The New York Times quotes Gerd Nonneman, professor of international relations at Georgetown University-Qatar campus, who says that the FBI and British intelligence have no doubt that this was fake news as a result of a hack. Qatar also says that the FBI is in Doha to help track down the source of these hacks.

The factors behind this crisis go back many years and stem primarily from Saudi Arabia’s frustration with Qatar’s Emirs, who fail to fall into lock-step with whatever Saudi Arabia wants for the region. This includes Qatar’s longstanding need to balance its Arab-Sunni ties with its neighbors alongside of its ties to Iran. It is exacerbated in recent years over the Arab uprisings and Qatar support for the Muslim Brotherhood in Egypt, and similarly its longstanding support for Hamas in Palestine. The current crisis is a stronger and potentially more catastrophic reaction to what Saudi Arabia, Kuwait, and Bahrain did in 2014; they removed their ambassadors to Qatar, in an attempt to force Qatar to “toe the line” and follow Saudi leadership in the Gulf, and end Qatar’s support for Islamists. Qatar’s diversions from the Saudi path are just some of the many disagreements over the past decades between these same players within the GCC and now increasingly beyond.

How might Iran respond to this situation? Do you think Iran will form a similar axis with Qatar, Russia, Syria, and other regional allies to counter this Saudi-led initiative?

This question takes on a very different meaning in the aftermath of Wednesday’s coordinated terrorist attacks in Tehran, Iran’s capital, which has not seen this level of violence since the 1980s. ISIS has claimed responsibility for these attacks, but Iran also blames Saudi Arabia—which would argue for a “yes” response to this question.

There is nothing pointing to that now, but that won’t stop Iran from further saber-rattling, just as Saudi is doing. And while I see this situation unraveling rapidly around the Gulf region, I also see that Qatar would not be keen on joining any such axis, if it were even proposed by Iran, given that Qatar is insisting that it is not anti-Saudi—or anti-UAE, Egypt, or Bahrain—and it is insisting on “kissing and making up,” if only the Saudis and their new anti-Qatar allies will agree to do so. But if the Saudi-led alliance against Qatar does not warm up to diplomatic initiatives by Kuwait, the U.S., Germany, or others, then it may not be Iran that tries to form such a counter-alliance; it might instead be our NATO ally Turkey. President Erdogan of Turkey on Wednesday announced his support for Qatar in this crisis; offered to provide urgently needed water and food supplies; and even considered sending 3,000 more Turkish troops to its existing military base in Qatar.