​Major-General Qassem Soleimani is dead – and what can Iran do?

The assassination of Major-General Qassem Soleimani is the most severe escalation of the ongoing tensions between the United States (US) and Iran thus far.
Soleimani has been the leader of the Iranian Revolutionary Guard Corps (IRGC) Quds Force since 1998, shaping Iranian international military operations and relations to countries in the region and proxy forces.  Soleimani was the most important personality within the IRGC  and within all the Iranian armed forces.
The assassination took place in Iraq and a prominent military leader for the Popular Mobilization Forces (PMF), Abu Mahdi al-Muhandis, was killed as well. The killing highlights a vital aspect of the conflict between the US and Iran, as the countries fight for influence in Iraq. The PMF consists mostly of Iranian-backed militias. In 2018, the Iraqi Prime Minister Adil Abdul-Mahdi decided to integrate these forces into the regular Iraqi armed forces. Meanwhile, the US supports the Iraqi government and armed forces with personnel, training and equipment.  Iraq is stuck in the middle between the US and Iran. Many attacks from both sides have taken place on Iraqi soil in the past year.

Ever since the US left the Iranian nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA) in 2018,  the tensions between the US and Iran have escalated. Iran has taken numerous steps away from the nuclear deal, while the European signatories have been working to keep the deal intact. Iran has captured, and attacked merchant vessels in the Strait of Hormuz, shot down a US drone, and has been accused of numerous other attacks while Iranian proxies in different countries continuously act out against US forces and allies.

The US has mostly responded with sanctions that have crippled the Iranian economy, while Israel has been accused of perpetrating several attacks on both Syrian and Iraqi soil against Iranian forces.

Previously, the most severe escalation happened on the 14th of September 2019 when several Saudi Arabian oil facilities were damaged in an attack by cruise missiles and drones. The Houthi forces of Yemen claimed the attack, but the attack didn't come from the direction of Yemen and both the US and Saudi Arabia quickly pointed their fingers at Iran as the perpetrator of the attack.

The United States has no problem attributing attacks to Iran, despite Iran's attempts to hide their involvement. Iran has been walking a thin line, acting as an aggressor in the region but avoiding armed conflict. All American forces and allies in the area are on high alert, making it practically impossible for Iran to act clandestinely. As the Iranian proxies in the region are well-known any action taken by the Houthi’s in Yemen, Hezbollah in Lebanon or the PMF in Iraq will be attributed to Iran.

​The question remaining is what Iran can do in retaliation for one of their most important commanders being killed, while still avoiding a conflict that would mean the end of the regime?