Photo taken on Sept. 24, 2018 shows military vehicles on a military operation against the Islamic State (IS) group in Watapur district of Kunar province, Afghanistan. (Photo: Xinhua)

US President Donald Trump on Sunday announced the death of Islamic State (IS) leader Abu Bakr al-Baghdadi in a US military operation in Syria.

IS emerged in Iraq as an al-Qaeda splinter group amid the US-led invasion of the country.

Al-Baghdadi, the group's leader, broke ties with al-Qaeda and renamed his group "the Islamic State of Iraq and the Levant" in 2013.

In 2014, the extremist group rapidly captured large territories in Iraq and Syria and declared a so-called "caliphate" in 2014, posing a dire threat to regional peace and stability.

Photo taken on Sept. 24, 2018 shows military vehicles on a military operation against the Islamic State (IS) group in Watapur district of Kunar province, Afghanistan.(Photo: Xinhua)

The following is a chronology of the international effort to defeat IS in the past five years.

-- On Sept. 10, 2014, the United States announced the formation of a broad international coalition to defeat IS.

-- On Sept. 23, 2014, US jets started bombing IS targets in Syria and carrying out airstrikes on the IS stronghold of Raqqa and other locations, along with foreign partners from Arab countries, including Bahrain, Saudi Arabia, the United Arab Emirates and Jordan.

-- On Sept. 16, 2016, the United States announced it had killed IS leader Wael Adel Salman, who had "direct access" to al-Baghdadi, in a Sept. 7 airstrike, just weeks after IS suffered a major loss when its chief spokesman Abu Muhammad al-Adnani was taken out in an air attack in the area of Aleppo, Syria.

-- On July 10, 2017, Iraq formally declared Mosul's liberation from IS after nearly nine months of fierce fighting to dislodge the extremist militants from Mosul, which was their last major stronghold in Iraq.

-- On Oct. 17, 2017, IS lost its de facto capital of Raqqa to the Syrian Democratic Forces (SDF), the first major defeat to the terror-designated group in the heartland of its control in northern Syria.

-- On Jan. 26, 2018, the United Nations Security Council Monitoring Team concerning IS published a report, concluding that the al-Qaeda network remains resilient and outlining the team's sanction measures against IS, including travel bans, asset freezes and arms embargoes.

Photo taken on July 14, 2019 shows the destroyed al-Nuri Mosque in the old city of Mosul, Iraq. The war for liberating Iraq's Mosul from the Islamic State (IS) militant group has achieved victory for two years, but its grave impacts still weigh heavily on the city's residents.(Photo: Xinhua)

-- In March, Trump claimed the "liberation" of all territory controlled by IS in Syria and Iraq, while vowing to remain vigilant until "it is finally defeated," as the SDF announced the defeat of the IS militant group in eastern Syria.