President Donald Trump ordered the killing of Iran's top military commander, Maj. Gen. Qassem Soleimani, in an airstrike last week, sparking a major escalation in tensions with Iran.

Some experts have raised concerns that tensions between the US and Iran may actually embolden a common enemy, the Islamic State, which may seek a resurgence amid the chaos created in Iraq.

Experts say the remaining followers of the Islamic State in Iraq may view Soleimani's death, along with the ensuing chaos on the ground, as a window of opportunity to strike.

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President Donald Trump ordered the killing of Iran's top military commander, Maj. Gen. Qassem Soleimani, in an airstrike last week, sparking a major escalation in tensions with Iran.

While experts widely debated Iran's anticipated response, the country took action early Wednesday by firing more than a dozen ballistic missiles at two bases in Iraq hosting US and Iraqi military personnel.

The missile strikes did not result in casualties, a move many observers speculated was intentional to retaliate against the US without prompting a full-blown war.

Trump on Wednesday touted the fact that the missile attacks resulted in no American or Iraqi deaths and left minimal damage to the Irbil and Al-Asad facilities as something "the American people should be extremely grateful and happy" for.

He added that Iran "appears to be standing down" and vowed that the US would not tolerate any malign behavior by it.

But some experts have raised concerns that tensions between the US and Iran may actually embolden a common enemy, the Islamic State, which could seek a resurgence amid the chaos created in Iraq.

Soleimani played a key role in the fight against the Islamic State in Iraq

Iranian Maj. Gen. Qassem Soleimani at a meeting with Supreme Leader Ayatollah Ali Khamenei and Revolutionary Guard commanders in Tehran, Iran, in 2016. (Office of the Iranian Supreme Leader via AP)

While the US and Iran have had no formal diplomatic relations since 1980, the two found unlikely common ground in the battle against the Islamic State.

The US-led military coalition helped train Kurdish fighters on the ground and conducted airstrikes against Islamic State positions in Iraq and Syria.

Iran, too, was deeply involved in the fight against Islamic State. In Syria, the country propped up the Assad government as Syria spiraled into civil war, and in Iraq the Iranian government was among the first to pledge assistance in battling the extremist group, deploying its own troops on the ground.

Iran's participation in the fight against ISIS largely stemmed from the country's desire to have more influence in the Middle East. It was also linked to the centuries-long ideological fight between two sects of Islam: Shiite and Sunni.

ISIS practices an extreme form of Sunni Islam called Salafism, and it does not consider Shiite Islam — which is the dominant strand of Islam in Iran and large portions of Iraq — to be true Islam.

Sunni Muslims, who consider themselves to be a more orthodox branch of Islam, represent a majority of the world's Muslims and make up about 90% of the populations of Egypt, Jordan, and Saudi Arabia.

Shiite Muslims represent a smaller population of the world's Muslims, though they are the majority in some Islamic countries, including Iran.

This sectarian conflict has been linked to many crises in the Middle East over the years, particularly because Iran has adopted a policy of supporting Shiite militias and governments through a vast network of proxies, putting it at odds with Sunni powers like Saudi Arabia.

Leaked documents published by The Intercept in November revealed a vast network of Iranian influence in Iraq, largely orchestrated by Soleimani.

These are the forces across the region that the Quds Force is known to support via things like advice, training, and armaments to spread Iranian influence and threaten adversaries like Israel and Saudi Arabia. Skye Gould/Business Insider

The Sunni-Shiite divide flared in the past decade as the Islamic State gained power in Syria and Iraq.

Soleimani rose to prominence during this time by advising Kurdish and Shiite forces in fighting the Islamic State. In 2014, Soleimani was credited with helping the Iraqi city of Amirli withstand an ISIS assault.

And though Iraqi Prime Minister Haider al-Abadi declared victory over the Islamic State in December 2017, a recent report indicates that ISIS may still have 14,000 to 18,000 members in Iraq and Syria, including up to 3,000 foreigners.

The group has signaled that followers of its ideology continue to exist, particularly during periods of unrest in its former strongholds. After Trump hastily pulled US troops out of Syria in October, the group took advantage of the chaos and launched an attack at an Iraqi oil field, prompting concerns of a resurgence.

The battle between Iran and the US playing out on Iraqi soil could give ISIS 'greater freedom of action'

Shiite paramilitary fighters with an Islamist State flag they pulled down during victory celebrations after returning from Tikrit in Kerbala, southwest of Baghdad, in 2015. REUTERS/Mushtaq Muhammed

Experts have warned that the conflict playing out between the US and Iran will only fuel further instability in Iraq, which is slowly recovering from the devastation brought on by the emergence of ISIS within its borders.

Lydia Khalil, a research fellow at the Lowy Institute in Sydney, told Business Insider that the fact the conflict between the US and Iran was playing out on Iraqi soil was a "complicating factor."

"Iraq has been a theatre for US-Iranian competition, influence, and power projection for some time," she said. "Iraq will remain and increase as a battlefield between US and Iran after this event, which will complicate Iraq's stabilization and governance."

Rodger Shanahan, also a research fellow at the Lowy Institute, said that considering Soleimani's "significant" role in battling the Islamic State in Iraq, his death had reverberated through the region.

A member of the Iraqi forces walking past a mural bearing the logo of the Islamic State in 2017 in a tunnel that was reportedly used as a training center by the jihadists. AHMAD AL-RUBAYE/AFP via Getty Images

Followers of the Islamic State in Iraq might now sense a window of opportunity to strike.

"They are looking to survive and carve out areas of influence within Iraq if possible," Shanahan said.

Shanahan said a total Islamic State resurgence would be surprising, and that Soleimani's death was "unlikely to embolden whatever supporters Islamic State has elsewhere," including active franchises in West Africa and Afghanistan.

But in Iraq — where the roots of the Islamic State were established in 2004 — the group has a chance at revival.

"Iraq is their heartland," Shanahan said. "Any diminution in coalition or Iraqi military actions will give them greater freedom of action."