On December 10, the US announced that its combat mission in Iraq has ended, four years after it helped defeat the jihadist Islamic group there.
The Islamic State emerged from the remnants of al Qaeda in Iraq, a local offshoot of al Qaeda founded by Abu Musab al Zarqawi in 2004.
The group which had faded into obscurity, began to reemerge in 2011 by taking advantage of the growing instability in Iraq and Syria.
In June 2014, Abu Bakr al Baghdadi announced the formation of a caliphate stretching from Aleppo in Syria to Diyala in Iraq, and renamed the group the Islamic State.
In 2015, ISIS expanded into a network of affiliates in at least eight other countries while its branches, supporters, and affiliates increasingly carried out attacks beyond the borders.
At its height, the Islamic State held about a third of Syria and 40 percent of Iraq and seemed invincible until a US-led global coalition reentered Iraq.
Between 2014 and 2015, a U.S.-led coalition began airstrikes against ISIS in Iraq under campaign “Operation Inherent Resolve” and expanded the campaign to Syria.
By 2016, the United States conducted more than 8,000 airstrikes in Iraq and Syria as ISIS suffered key losses in Iraq and along Syria’s border with Turkey
By December 2017, the Islamic State had lost 95% of its territory, including its two biggest cities, Mosul, Iraq’s second largest city, and Raqqa, Syrian nominal capital.
In 2018, the focus of the campaign against ISIS shifted to eastern Syria, where a U.S.-backed coalition of Syrian Kurds and Arabs captured key ISIS positions.
On December 19, 2018, President Donald Trump declared that ISIS was defeated and signalled his intention to withdraw all 2,000 U.S. troops in Iraq and Syria.
The Baghdadi era of ISIS ended on October 26, 2019, when the leader of the terror group was killed in a U.S. raid in northern Syria.
The US says the 2,500 troops currently in the country will remain to “advise, assist and enable” Iraqi security forces, at the government’s invitation.
Shobhil Shrivastava 
Aayush Pal