WASHINGTON - The killing of Qassem Soleimani in a U.S. airstrike Friday is a devastating blow to pro-Iranian militias across the Middle East, some experts said, warning that the militia groups could turn the region into further chaos through retaliation violence.

The powerful Iranian general, along with Iraqi Shiite militia leader Abu Mahdi al-Muhandis and several other aides, was struck at the Iraqi Baghdad airport in a U.S. operation directed by President Donald Trump. The killing has been received with rage among the Shiite groups, with the Iranian government vowing “a crushing revenge” against the U.S.

Experts Warn Soleimani Killing Could Prompt Chaos in Middle East

“Iran’s web of patron-client relationships and proxies was largely Soleimani’s creation, and it was he who brilliantly developed and managed these relationships to Tehran’s advantage,” said Jonathan Spyer, a research fellow at Philadelphia-based think tank the Middle East Forum.

Experts Warn Soleimani Killing Could Prompt Chaos in Middle East

Spyer said that Soleimani used informal relations developed over a long period of time with Shiite militia leaders across the Middle East. Such relationships, he added, cannot easily be bequeathed to a successor.

Experts Warn Soleimani Killing Could Prompt Chaos in Middle East

Iran’s Supreme Leader Ayatollah Ali Khamenei Friday appointed Brigadier-General Esmail Ghaani to replace Soleimani as the new commander of the Islamic Revolutionary Guard Corps-Quds Force. Khamenei said in a statement that Ghaani was among “the most prominent” IRGC commanders and will continue Soleimani’s path in directing the Quds Force.

The Quds Force is an IRGC unit responsible for undertaking Iran’s external operations to advance the Islamic regime’s revolutionary values. Under Soleimani’s command, the unit has succeeded in expanding Iran’s influence in the so-called Shiite Crescent, a term referring to a crescent-shaped region in the Middle East where Shiite communities reside.

Max Abrahms, a nonresident fellow at the Quincy Institute, a Washington-based think tank, told VOA that Soleimani had made sure militant actions by Shiite groups were carefully assessed.

“Although it is very understandable that Soleimani would be associated with violence, what people don’t understand is that the IRGC could have produced over the years much more violence in many more places against a variety of different targets, but chose not to, and the reason is because the leader did not give a green light,” Abrahms said.

“What concerns me is now that we’ve taken out Soleimani, we are going to see an uptick in violence that will be more indiscriminate than in the past,” he added.

In Lebanon, where Iran has empowered Shiite Hezbollah group since its founding in 1985, the group’s head, Hassan Nasrallah, Friday mourned Soleimani as a “master of resistance.”

“To continue on General Soleimani’s path, we’ll raise his flag in all battlefields,” Hezbollah-linked al-Manar website quoted him as saying.

According to the Atlantic Council’s senior fellow Nicholas Blanfold, Hezbollah’s extensive networks across the Middle East, Latin America, Europe and Africa make it indispensable for Iran’s global outreach.

The Iranian regime “through the networks, particularly Hezbollah, which has a global reach, could affect a kind of retaliatory operation almost anywhere around the world,” Blanfold told VOA.

U.S. officials say that Iran for years has funded Hezbollah with an estimated $700 million annually. The funds and arms support have helped the group sustain years of violence against Israel, they said.

In Iraq, experts say Soleimani played a decisive role in organizing Shiite militias following the U.S. invasion in 2003 and the rise of the Islamic State in 2014.

“What you’ve lost basically is the brain, he is the brain of Shia militias in Iraq,” said Boston-based Iraq military expert Michael Knights of the Washington Institute. He added that Soleimani played a role as a centralizing force to unify some 50 militias that would have been otherwise divided under the umbrella of Iraqi Popular Mobilization Forces.

“It’s going to open up a lot of opportunity, rivalry and competition. If Muhandis died on his own, they would have turned to Soleimani to tell them who is the next leader. Losing them both is really a time of fracture for them,” he told VOA.

Babak Taghvaei, a Malta-based military analyst, told VOA that some Iraqi Shiite militias with nationalist sentiments in the past have shown their willingness to drift away from Iran. Soleimani’s death provides Iraqi leaders an opportunity to encourage those to join the democratic system in the future, Taghvaei argued.