The US killing of top Iranian general Qasem Soleimani and Iran’s retaliatory missile attack have heightened fears of a conflict with far-reaching implications.
Who loses or gains from the crisis could change rapidly depending on what the US and Iran do next.
So, who are the winners and losers?
Despite the loss of such a powerful military figure, Iran could be a short-term beneficiary of Qasem Soleimani’s killing.
The general’s death, and the massive funeral processions that followed, have allowed Tehran to shift public attention away from a violent government crackdown on protests over rising petrol prices in November.
It also allows Iran to demonstrate its ability to rally at a time of crisis, with its notoriously divided political elite pulling together.
Iran has been under economic pressure from renewed US sanctions following President Trump’s withdrawal from the Iran nuclear agreement in 2018.
Last year, the situation escalated after Iran downed a US drone and detained shipping tankers. It was also accused of sponsoring missile attacks such as September’s strike on Saudi oil facilities – something it denied.
Iran has already hit back at America with a missile strike targeting US troops in Iraq. The country may benefit if it drags out any further retaliation and instead continues to play on public sympathy and anxiety over what comes next.
However, if the country does take further action, it may no longer be seen as a winner.
Depending on where and how Iran seeks to further avenge Soleimani’s death, Tehran, a lesser military power, could find itself in a damaging military cycle of action and reaction with the US.
Already subject to heavy sanctions and under pressure to comply with the nuclear agreement, continued escalation could further isolate Iran.
The Trump administration may have succeeded in denting Iran’s military prowess, while potentially boosting the President’s chance of re-election in November.
It has also sent a message of strength and solidarity to allies such as Israel and Saudi Arabia.
But if it is drawn into a tit-for-tat military action this could increase oil prices, lead to further loss of American life and spark another long-running regional war.
This could have ramifications for many other nations in the Middle East and beyond.
Shia forces in Iraq
In the short run, Iran-backed Shia militia in Iraq could benefit from the current crisis.
Over the past few months, the Iraqi government has been the target of many protests over Iran’s influence in the country, alongside complaints of poor governance and corruption.
These militias – and the rest of Iraq’s political establishment – are using the death of Soleimani to win back lost influence and legitimise their need to remain in the country.
The pledge to expel US troops from Iraq has long been a rallying cry of these groups and plays into the hand of their leaders.
It also creates a security vacuum for terrorist groups such as IS and Al Qaeda to exploit.
Iran and Israel have long been in conflict over their interests in the Middle East, and Iran’s desire to remove the Jewish state.
From Israel’s perspective, many threats still remain. These include Iran’s support for Israel’s adversaries such as Lebanon militant group Hezbollah and Syrian President Bashar al-Assad.
However, the death of Soleimani does indicate America’s growing intention to contain Iran.
In Israel, this is likely to be seen as a positive step that will benefit its security interests against Iran and the groups it supports.
“Israel stands with the United States in its just struggle for peace, security and self-defence,” the country’s Prime Minister Benjamin Netanyahu said after the attack.
Protesters in the Middle East
The looming threat of conflict will give Middle Eastern governments an excuse to curb protests throughout the region.
In particular, the recent protests in Iraq, Lebanon and Iran over issues such as unemployment and corruption will be contained using the justification of national security.
Governments could even go one step further and use the looming crisis to justify crackdowns on political activists and put the brakes on any attempts at political reform.
Saudi Arabia and the United Arab Emirates
Saudi Arabia and the United Arab Emirates (UAE) are in a precarious position.
Both were directly affected by last year’s shipping attacks in the Straits of Hormuz, and strikes on two major Saudi oil facilities, largely thought to be the work of Iran or Iranian-backed forces. Iran itself denied any involvement.
In response, the UAE attempted to ease the situation with Tehran, while Saudi Arabia has continued to support maximum pressure from Washington.
Since Soleimani’s killing, both countries have called for calm and de-escalation, with the Saudi defence minister travelling to Washington for talks with the Trump administration.
But their geographic proximity to Iran and their history of tensions makes them vulnerable to possible Iranian attack.
Already struggling to sustain the fragile Iran nuclear agreement, Europe remains in an awkward middle ground between the US and Iran.
The UK was not given advance warning of the drone strike by Washington, suggesting ongoing transatlantic tensions or at least lack of communication.
At the same time, having co-operated in the fight against IS, several European countries with troops in Iraq are liable to be drawn into the crossfire there if Iran chooses a military response.
The killing of Soleimani should ultimately remind us that the governance and regional stability issues that sparked the Arab Spring protests almost a decade ago remain unresolved.
About this piece
This analysis piece was commissioned by the BBC from an expert working for an outside organisation.
Dr Sanam Vakil is deputy head and senior research fellow with the Middle East and North Africa Programme at Chatham House. Follow her @SanamVakil
Chatham House, the Royal Institute of International Affairs, describes itself as an independent policy institute helping to build a sustainably secure, prosperous and just world.
Edited by Eleanor Lawrie