The latest offensives against IS, which has carried out brazen attacks in Europe, come as the jihadist group claimed suicide attacks on the Brussels airport and a metro station that killed 31 people.
"The more IS loses territory in Syria, the more they will export attacks," a senior French counter-terrorism official warned this week after the Belgium bombings.
Here are the key IS losses since January 2015:
- Syria's Kobane recaptured -
After a series of victories, IS suffers its first serious setback on January 26, 2015, in Kobane, a Syrian town near the border with Turkey known in Arabic as Ain al-Arab.
Kurdish forces backed by intense US-led air strikes capture the town after four months of fighting.
In June, Syrian Kurds also captured Tal Abyad, another town near the border that controls a supply route to Raqa, the IS de facto capital in northern Syria.
- Iraq retakes Saddam's home town -
Iraqi troops, police and Shiite-dominated paramilitary forces retake Tikrit, the home town of the late dictator Saddam Hussein, on March 31.
The operation, at that time the largest by Iraqi forces against IS, was helped by the fact that much of Tikrit's 200,000 residents had fled the city.
- Kurds cut key IS corridor -
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On November 13, Iraqi Kurds backed by US-led coalition air strikes drive IS out of Sinjar, northwest of Baghdad, cutting one of the group's crucial supply lines between Iraq and Syria.
IS had seized Sinjar in August 2014 and carried out a brutal campaign against its Yazidi minority that included massacres, enslavement and rape.
- Ramadi falls -
Iraqi troops retake a key district of the Sunni Arab city of Ramadi on December 8. Two weeks later the troops backed coalition air strikes reach the city's centre.
Ramadi is the capital of Anbar province, Iraq's largest which stretches from the borders with Syria, Jordan and Saudi Arabia to just west of Baghdad.
IS had seized Ramadi the previous May following an assault by dozens of suicide bombers driving explosives-rigged vehicles.
- Mosul and Palmyra -
On Thursday, Iraqi forces ousted jihadists from villages south of Mosul, IS's main hub in the country.
The army says the operation was the first phase of an offensive to recapture Nineveh province and its capital Mosul.
In Syria, regime forces backed by Russian warplanes and allied militia enter the IS-held ancient city of Palmyra.
Its recapture would be a major strategic and symbolic victory for the Syrian regime, since whoever holds it also controls the vast desert extending from central Syria to the Iraqi border.
Known as the "Pearl of the Desert", the city was overrun by IS in May, 2015 and since then the jihadists have blown up UNESCO-listed temples and looted ancient relics.