The renewed tensions between the U.S. and Iran dominated headlines in the first week of 2020, creating uncertainty, rumours, and perhaps inevitably, Internet memes about World War 3.

But what really happened? Here's how the recent conflict began.

Late December: U.S. trades blows with Iranian proxies

On Dec. 27, 2019, American defence contractor Nawres Hamid was killed in a rocket attack on an Iraqi military base in the city of Kirkuk, NBCNews reported.

However, it was not immediately clear who was responsible for the attack, and an investigation into the matter was opened by Iraqi security forces, according to the Financial Times (FT).

Then on Dec. 29, 2019, the U.S. carried out three airstrikes on an Iranian-backed Iraqi militia known as Kata'ib Hezbollah, holding them responsible, The Guardian reported.

25 fighters were reportedly killed in the airstrikes, described by U.S. Secretary of State Mike Pompeo as "defensive strikes" against jeopardising actions by Iran.

In response, Kata'ib Hezbollah vowed revenge while an estimated 6,000 Iraqi protesters gathered outside the U.S. embassy on Dec. 31 to demonstrate against the airstrikes, and tried to force their way into the embassy, CBSNews reported.

On the same day, U.S. President Donald Trump blamed Iran for Nawres's death and the protest outside the embassy, adding that "(Iran) will be held fully responsible."

Iran killed an American contractor, wounding many. We strongly responded, and always will. Now Iran is orchestrating an attack on the U.S. Embassy in Iraq. They will be held fully responsible. In addition, we expect Iraq to use its forces to protect the Embassy, and so notified!

— Donald J. Trump (@realDonaldTrump) December 31, 2019

Jan. 3: Iran's top general killed in a drone strike

Things escalated when senior Iranian general Qassem Soleimani was killed in a drone strike outside Baghdad International Airport in Iraq, early Friday morning, Jan. 3 (Singapore time).

Soleimani was the commander of the Quds Force, an elite unit within Iran’s Revolutionary Guards Corps, a branch of the Iranian armed forces.

The Quds Force is responsible for clandestine operations, unconventional warfare, and intelligence activities.

Soleimani had been reportedly involved in Iranian military activity in Syria, where he advised forces loyal to President Bashar al-Assad and also in Iraq, supporting Shia militiamen who fought the Islamic State (ISIS), according to the BBC.

He was also seen as having close relations with Iran’s Supreme Leader, Ayatollah Ali Khamenei, and was touted as a potential future leader of the country.

The Pentagon released a statement that said Soleimani had been responsible in "actively developing plans to attack American diplomats and service members in Iraq and throughout the region". 

Iran's foreign minister, Javad Zarif, condemned the attack as "extremely dangerous" and a "foolish escalation."

The US' act of international terrorism, targeting & assassinating General Soleimani—THE most effective force fighting Daesh (ISIS), Al Nusrah, Al Qaeda et al—is extremely dangerous & a foolish escalation.

The US bears responsibility for all consequences of its rogue adventurism.

— Javad Zarif (@JZarif) January 3, 2020

Jan. 5: Iran declares intention to pull back from nuclear deal entirely

On Jan. 5, Iran stated that it would step back from abiding by any limits to uranium enrichment under the 2015 nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA), Aljazeera reported.

The JCPOA had been negotiated between Iran, Germany and the five permanent members of the United Nations Security Council.

However, Iran added that it would continue to cooperate with the International Atomic Energy Agency (IAEA), and that steps taken to enriched uranium could be reversed if the U.S. lifted sanctions on Iran.

Tens of thousands of Iranians reportedly took to the streets to mourn Soleimani as his body arrived back in Iran. A total of three days of mourning was declared by Iran's Supreme Leader, Ayatollah Ali Khamenei, Al-Monitor reported.

Separately, Trump threatened that should Iran retaliate, the U.S. will target 52 cultural sites in Iran, as a representation of the 52 Americans who were taken hostage for more than a year during Iran's Islamic Revolution in 1979.

....targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level & important to Iran & the Iranian culture, and those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD. The USA wants no more threats!

— Donald J. Trump (@realDonaldTrump) January 4, 2020

Trump's threat came under heavy criticism, including from Americans, as attacking cultural sites is against international law.

He eventually walked back the threat, saying that he "liked to obey international law", Axios reported.

Jan. 7: Iran attacks two military bases in Iraq housing U.S. troops

On Jan. 7, Iran fired 22 missiles at two military bases in Iraq housing U.S. troops, the New York Times (NYT) reported.

No American or Iraqi casualties were reported in the strike, according to the NPR.

Trump struck an optimistic tone by tweeting, "All is well!"

All is well! Missiles launched from Iran at two military bases located in Iraq. Assessment of casualties & damages taking place now. So far, so good! We have the most powerful and well equipped military anywhere in the world, by far! I will be making a statement tomorrow morning.

— Donald J. Trump (@realDonaldTrump) January 8, 2020

However, he also defended his decision to kill Soleimani by stating that he was “the world’s top terrorist” who “should have been terminated long ago."

A note of restraint was also struck by Zarif, who stated:

"Iran took & concluded proportionate measures in self-defense. We do not seek escalation or war, but will defend ourselves against any aggression."

Iran took & concluded proportionate measures in self-defense under Article 51 of UN Charter targeting base from which cowardly armed attack against our citizens & senior officials were launched.

We do not seek escalation or war, but will defend ourselves against any aggression.

— Javad Zarif (@JZarif) January 8, 2020

In Singapore, the Straits Times reported that petrol prices had risen by three cents to a litre since the news of Soleimani's assassination, which was attributed to uncertainty over Iran's response.

Jan 8: Ukraine International Airlines plane crashes in Iran

On Jan. 8, a Boeing 737 belonging to Ukraine International Airlines crashed after take-off from Iran’s Imam Khomeini Airport.

Initially, technical problems were reported to be the cause.

However, both Trump and U.S. intelligence subsequently stated they believed that the plane had been accidentally shot down by Iran.

Singapore shares took a hit from the rising tensions, with the Straits Times Index falling 1.23 per cent on Jan. 8.

Jan. 11: Iran admits it shot down plane by mistake

Despite initially questioning the U.S. allegations, on Jan. 11, the Iranian military admitted to "unintentionally" shooting down the Ukrainian International Airlines plane.

In response, Iranian citizens took to the streets of several cities in the country to protest against the government, the BBC reported.

According to Politico, the plane had been shot down amidst Iran's anticipation of a possible retaliation for hitting two bases in Iraq housing U.S. forces with ballistic missiles.

The head of Iran's Revolutionary Guard issued an emotional apology in parliament, stating:

"I swear to almighty God that I wished I was on that plane and had crashed with them and burned but had not witnessed this tragic incident. I have never been this embarrassed in my entire life. Never."

Meanwhile, Trump took to tweeting his support for the Iranian protesters in Farsi, as well as warning Iran's leaders to avoid killing the protesters.

به مردم شجاع و رنج کشیده ایران: من از ابتدای دوره ریاست جمهوریم با شما ایستاده‌ام و دولت من همچنان با شما خواهد ایستاد. ما اعتراضات شما را از نزدیک دنبال می کنیم. شجاعت شما الهام بخش است.

— Donald J. Trump (@realDonaldTrump) January 11, 2020

Translation, as per The Washington Examiner:

"To the brave and suffering Iranian people: I have stood with you since the beginning of my presidency and my government will continue to stand with you. We are following your protests closely. Your courage is inspiring."

خطاب به رهبران ايران: معترضان خود را نكشيد. هزاران تن تاكنون به دست شما كشته يا زنداني شده اند، و جهان نظاره گر است. مهمتر از ان، ايالات متحده نظاره گر است. اينترنت را دوباره وصل كنيد و به خبرنگاران اجازه دهيد ازادانه حركت كنند! كشتار مردم بزرگ ايران را متوقف كنيد! https://t.co/rzpx3Nfn03

— Donald J. Trump (@realDonaldTrump) January 12, 2020

Events so far:

Top image collage left photo from HO / IRANIAN SUPREME LEADER'S WEBSITE / AFP, right image by BRENDAN SMIALOWSKI/AFP via Getty Images