“It is impossible to overstate the importance of this particular action,” said Petraeus. “It is more significant than the killing of Osama bin Laden or even the death of [ISIS leader Abu Bakr] al-Baghdadi.”

The former CIA director stressed that Soleimani was the “architect and operational commander” of Iran’s efforts to establish control over the region. The Quds Force commander provided arms and munitions that killed over 600 American soldiers and many other coalition partners in Iraq, Syria and other countries.

Petraeus told Foreign Policy that it seems the airstrike was carried out to show that the US “is just not going to allow the continued violence,” including rocket attacks on US bases and attacks on shipping routes and unarmed drones, “without a very significant response.”

The former general called the assassination a “very significant effort to reestablish deterrence,” which had not been built up by the “relatively insignificant” responses that have been carried so far.

“Obviously, all sides will suffer if this becomes a wider war, but Iran has to be very worried that… this is a real threat to the regime in a way that we have not seen prior to this,” said Petraeus, adding that with the state of Iran’s economy, they have to be “very leery, very concerned that that could actually result in the first real challenge to the regime, certainly since the Iran-Iraq War.” Petraeus added that Iran’s Supreme Leader Ayatollah Ali Khamenei has to consider the fact that the Iranians aren’t nearly as supportive of the regime as they were during the Iran-Iraq War, before deciding on the response to the assassination “Obviously, all sides will suffer if this becomes a wider war, but Iran has to be very worried that… this is a real threat to the regime in a way that we have not seen prior to this,” said Petraeus, adding that with the state of Iran’s economy, they have to be “very leery, very concerned that that could actually result in the first real challenge to the regime, certainly since the Iran-Iraq War.”

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The former general stressed that Iran doesn’t know where things will go from here any more than anyone else does. “There could be actions in the gulf, in the Strait of Hormuz by proxies in the regional countries, and in other continents where the Quds Force has activities,” said Petraeus. ”There’s a very considerable number of potential responses by Iran, and then there’s any number of potential US responses to those actions.”

Soleimani and Iraqi militia commander Abu Mahdi al-Muhandis, along with at least 10 other people, were killed in a US airstrike in Baghdad on Thursday.

"At the direction of the President, the US military has taken decisive defensive action to protect US personnel abroad by killing Qasem Soleimani, the head of the Iranian Revolutionary Guard Corps-Quds Force, a US-designated Foreign Terrorist Organization," the Pentagon wrote in a statement.

On Sunday, US President Donald Trump warned that “if Iran strikes any Americans, or American assets, we have targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level and important to Iran and the Iranian culture, and those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD."

US Secretary of State Mike Pompeo stated that the US airstrike on Soleimani was necessary and that not taking action would have posed a greater risk.

Reuters contributed to this report.

Former CIA director and US General David Petraeus stressed that the assassination of IRGC Quds Force commander Qasem Soleimani is more important than the killings of Osama bin Laden or ISIS leader Abu Bakr al-Baghdadi, according to Foreign Policy.