The US Iran conflict not over yet
An Iranian military response to the American drone assassination of its top general, Qassem Soleimani, on 3 January 2020 was inevitable given the domestic pressure Tehran has been under to retaliate once the funeral was over.
Not retaliating would also have lowered Iran's regional standing.
It seems the Trump Administration regarded killing Major-General Soleimani as a justifiable action given the role he played in countering US influence in Iraq and Syria, but it probably underestimated his hero-worship stature in Iran and revered status among regional Shiite groups.
In April 2019, the US declared the Iranian Revolutionary Guard Corps (IRGC) a "foreign terrorist organisation" to put more pressure on the Iranian regime. Major-General Soleimani commanded the IRGC's 15,000 strong Quds Force, responsible for the kinds of extraterritorial and covert operations undertaken by Special Forces in Western armies.
In US eyes, the declaration made Soleimani the leader of a terrorist organisation and a legitimate assassination target. (The only allied country that endorsed the American declaration was Canada.)
The targeted killing of Soleimani was the first time the US had assassinated a senior officer in another country's military since 1943, when it killed Japanese Admiral Yamamoto in revenge for the Pearl Harbor attack - but that was during an ongoing war.
Pentagon officials were reportedly stunned when Trump authorised the strike on Soleimani.
During the conflict against Sunni Islamic State (IS) in Iraq and Syria, Iranian-backed Shiite militias had been in the forefront in countering IS, so ironically the US and Iran were fighting on the same side for about three years. However, clearly the ancient proverb "the enemy of my enemy is my friend" did not stand the test of time.
In May 2018 President Trump unilaterally abandoned the 2015 Iranian nuclear deal before reinstating economic sanctions against Iran. He threatened to do the same to countries and firms that continued to buy Iran's oil. In consequence, Iran's economy fell into a deep recession.
Relations between the US and Iran worsened in May 2019 when the US tightened sanctions on Iran's oil exports.
In response, Iran began covert retaliation. In May and June 2019, explosions hit six oil tankers in the Gulf of Oman. The US accused Iran of being responsible; Iran denied involvement.
On 20 June 2019, Iranian forces shot down an American drone over the Strait of Hormuz. The US claimed it was over international waters, but Iran says it was over Iranian territory.
Since then, according to US intelligence sources, Quds Force-trained Shiite militia forces in Iraq have been preparing to attack US forces in Iraq.
The Trump Administration's response to the fallout from Soleimani's assassination was characteristically clumsy.
There was denial of an unsigned letter from the US Commander of Task Force - Iraq sent to Iraqi officials implying that US troops were preparing to leave Iraq in response to Iraqi demands. It was an unapproved "draft" according to the Pentagon.
Then there was President Trump's threat to hit Iranian cultural sites that left his top advisers scrambling to convince people that no war crime was intended. (Presumably Trump was not aware of the world heritage status of Persian cultural sites.)
There were also questions about intelligence that suggested "imminent" Shiite militia attacks on US facilities in Iraq.
At the same time, the US's refusal to give Iran's Foreign Minister Zarif an entry visa to attend a UN Security Council meeting in New York was a clear breach of the US agreement with the UN.
To make matters worse for the Trump Administration, there was little public support from allies who had been kept in the dark about US plans to kill Soleimani. Nor apparently were members of the US Congress informed.
The Iranian retaliatory missile attacks on Ain al-Assad and Irbil Airbases occurred at around 9.30am AEST on 8 January (1.30am in Iraq). The attack involved 15 missiles launched from Iran, of which 10 hit the extensive Ain al-Assad Airbase and one the Erbil base. Four failed.
For Iranian domestic consumption state television claimed 80 "American terrorists" had been killed and US helicopters and military equipment damaged. Iran announced publicly it did not intend to take further retaliatory action for the killing of Soleimani.
In reality, the Iranian missiles did not cause any American casualties or much damage, and analysts believe that Iran deliberately avoided causing casualties.
President Trump in his subsequent address to the nation appears to have ruled out an American military response, but declared that the US would impose additional economic sanctions on Iran.
That looks to be the end of the matter from a military tit-for-tat perspective, but Iran will probably now organise deniable attacks against US facilities and personnel in the region - such as rocket attacks by proxies, that will make US military retaliation harder to justify.
Clive Williams is a visiting professor at the ANU's Centre for Military and Security Law.