Here are key developments in the war against the Islamic State group as Iraqi forces launch an assault on Fallujah, a key IS stronghold west of Baghdad.
The top US general for the Middle East has also paid a surprise visit to American soldiers advising Syrian rebel groups as they prepare to attack IS in Raqa, the jihadist group's other main stronghold.
The first air strikes
On August 8, 2014, US jets strike IS positions in northern Iraq in response to an appeal from Baghdad, in the first American military operation in the country since troops withdrew in late 2011.
Already entrenched in neighbouring Syria, IS seized swathes of Iraqi territory in a lightning offensive launched in June 2014 and marked by a complete collapse of the security forces.
On September 5, US President Barack Obama vows to build "a broad, international coalition" to defeat IS.
On September 23, the US and Arab allies launch air strikes on IS in Syria.
IS driven out of Kobane
On January 26, 2015, IS is driven out of the Syrian border town of Kobane after more than four months of fighting led by Kurdish forces backed by coalition air strikes.
On the same day, an Iraqi military official says that the eastern province of Diyala has been liberated.
Iraq's Tikrit recaptured
On March 31, 2015, Baghdad announces the "liberation" of Tikrit, 160 kilometres (100 miles) north of Baghdad. Government forces backed by Shiite militias had launched their offensive on March 2 against the IS, which had controlled it for nearly 10 months.
But in May, the IS takes Iraqi provincial capital Ramadi, and then Syria's famed ancient city of Palmyra, a UNESCO World Heritage site.
IS ousted from border town
On June 16, 2015, Kurdish militia backed by Syrian rebel forces and coalition air strikes seize the Syrian border town with Turkey of Tal Abyad from IS, which had occupied it for more than a year.
Tal Abyad was one of two main transit points on a key supply route to de facto IS capital Raqa.
Turkey declares war on IS
On July 24, 2015, Turkish warplanes bomb IS positions inside Syria for the first time in a dramatic toughening of Ankara's stance.
But the Turkish raids are largely aimed at positions of the Kurdistan Workers Party in Iraq and Syria.
Turkey gives Washington the green light for American warplanes to fly operations over Syria from its strategic southeastern air base of Incirlik.
Russia intervenes in Syria
On September 30, 2015, Russia launches air strikes in Syria in what it calls a campaign against "terrorists" to help its Damascus regime ally.
Washington accuses Moscow of mainly targeting Syrian rebels.
Iraq's Sinjar, Ramadi retaken
On November 13, 2015, Iraqi Kurds announce the "liberation" of Sinjar from IS in an assault backed by US-led strikes that severs a key jihadist supply line with Syria. Across the border, a coalition of Arab and Kurdish fighters drives IS out of the village of Al-Hol, also on the supply route.
On December 27, Iraqi forces retake Ramadi.
Syrians retake Palmyra
On March 27, 2016, Syrian forces backed by Russia retake Palmyra, but the jihadists manage to isolate the city again on May 10.
US tally of IS retreats
On May 16, a Pentagon spokesman says the IS has lost around 45 percent of its territory in Iraq, and between 16-20 percent of land it occupied in Syria. Meanwhile, the US-led coalition continues to target top IS officials.
