Even the possibility that the U.S. directly targeted Soleimani especially on Iraqi soil sent shockwaves around the globe, spiking oil prices and leading to instant assessments of the potential fallout. U.S. officials have long depicted Soleimani as a paramilitary and terrorist mastermind, deemed responsible for attacks on American troops in Iraq and against U.S. interests all over the world.

Some current and former U.S. officials, as well as veteran Iran observers, said the killing was an escalatory move far beyond what theyd expected.

Theres no chance in hell Iran wont respond, said Afshon Ostovar, an expert on Soleimani and author of Vanguard of the Imam a book about Irans Islamic Revolutionary Guard Corps.

The strike, which also reportedly killed Iraqi militia commander Abu Mahdi al-Muhandis, who was traveling in the same convoy as Soleimani, even astonished some members of the Trump administration who said killing the Iranian general had never been seriously considered.

I cant believe it, one U.S. official said. The immediate concern for me is: Whats the next step from Iran? Is this the beginning of a regional conflagration?

Supreme Leader Ayatollah Ali Khamenei, left, Iraqi Shiite cleric Muqtada al-Sadr, center, and commander of Iran’s Quds Force, Qassim Soleimani. | Office of the Iranian Supreme Leader via AP

A former U.S. official who dealt with the Middle East said the strike was especially notable because it targeted the leader of a state apparatus, as opposed to a non-state actor.

We need to be prepared that were now at war, he said.

A second Middle Eastern official said that a retaliation by Iran known for its own assassinations abroad could occur anywhere.

It could be targets in Africa, it could be in Latin America, it could be in the Gulf, it could be anything, the official said. I dont think theyre going to take the assassination of one of their key guys and just turn the other cheek.

Soleimani had been leading the Quds Force, a unit of Irans Islamic Revolutionary Guard Corps that is behind much of Irans military actions outside its borders. He was a hugely popular figure in Iran, and a frequent rhetorical target of President Donald Trump and his aides.

Secretary of State Mike Pompeo, for instance, repeatedly singled out Soleimani for criticism as part of the Trump teams broader anti-Iran maximum pressure campaign.

That campaign has intensified in recent months, as the U.S. has clashed with Iran and its proxies. Just days ago, an American contractor died in Iraq after an attack by an Iraqi militia allied with Iran. The U.S. responded by bombing sites held by the group, killing some two dozen militiamen.

Within days, protesters believed to be linked to the Iran-backed militia breached parts of the U.S. Embassy compound in Baghdad. The Iraqi government, meanwhile, condemned the U.S. airstrikes, noting that the militia had ties to its own security forces.

But the death of Soleimani was a shocking development, even considering how tense U.S.-Iran relations have grown under Trump. The president has heaped economic sanctions on Irans Islamist regime and at times threatened Tehran with military action.

Trump also pulled the United States out of the internationally negotiated nuclear deal with Iran, saying it was too narrow and should have curbed Irans non-nuclear aggressions in the region as well as its nuclear program.

The two countries nearly came to a direct military clash earlier this year after Iran was blamed in a string of attacks on international oil tankers. The U.S. and Iran even downed each others drones, but Trump backed down at the last minute from staging a military strike directly on Iran.

Though he has sent thousands more troops to the region, Trump has said repeatedly that he doesnt want to engage in a new war in the Middle East. But the possibility that Iran will feel compelled to respond with escalatory actions of its own could embroil the president in a politically risky confrontation in the middle of an election year.

The death of Soleimani is also likely to have deep implications in Iraq and other countries in the region, where Iran has powerful political allies and proxy forces.

The most immediate shock waves are likely to be felt in Iraq, which for years has been a battleground for influence between Washington and Tehran. One of Irans longstanding foreign policy goals has been to push U.S. troops out of Iraq, where theyve maintained a presence since the 2003 invasion that toppled dictator Saddam Hussein.

Many Iraqis are sick of Iranian influence in their country. Recent widespread demonstrations have featured chants against Tehran and the Shiite clerics who largely run its religion-infused regime.

But Iraq also wants to avoid becoming ground zero for a U.S.-Iran war, while keeping up friendly relations with Iran to help its own economy.

It is only fair for Iraq to strive to achieve this balance but given the beef between Iran and the U.S. its a lost effort, a former Iraqi diplomat told POLITICO. The Trump administration is on a zero-sum mission vis a vis Iran, and expects Iraq to pick one side only.

Trumps hard line toward Iran has earned applause from other Middle Eastern countries, notably Israel, Saudi Arabia and the United Arab Emirates, which consider Iran an implacable enemy bent on manipulating the region in its favor.

Still, Saudi and UAE diplomats in recent months have tried to cool tensions with Iran. And while theyre likely to shed few tears for Soleimani, they may worry about the blowback Iran and its allies are capable of creating in their own countries.