Battle for Iraq and Syria in maps
- 10 February 2016
- From the section Middle East
Islamic State (IS) militants made some major territorial gains in south-western Syria in 2015 - but they lost several key towns in Iraq, as well as parts of Syria's northern border with Turkey.
The rapid advance by the groups militant fighters threw the region into chaos in 2014 and led to the launch of air strikes on IS targets in Iraq by a coalition of countries headed by the US in August 2014 and in Syria a month later.
The jihadist group, which has fighters from across the world, announced the establishment of a "caliphate" - an Islamic state - stretching from Aleppo in Syria to the province of Diyala in Iraq.
See where IS have made territorial gains and losses, Jan-Dec 2015
Russia began carrying out air strikes in Syria in September 2015 after a request for help from Syrian President Bashar al-Assad, who has clung on to power despite more than four years of civil war.
How many strikes have been carried out? What are the targets?
The US-led coalition has launched more than 6,600 air strikes against IS targets in Iraq since its campaign began on 8 August 2014. The UK launched its first air strikes in Iraq on 30 September 2014.
In neighbouring Syria, the US, along with Bahrain, Jordan, Qatar, Saudi Arabia and the United Arab Emirates, has also carried out more than 3,200 attacks on IS-held areas since 22 September 2014.
France began air strikes against IS in Syria in September 2015. The UK launched its first air strikes against IS in Syria in December 2015.
Russia is not part of the US-led coalition, but its aircraft also began air strikes in Syria on 30 September 2015, as well as launching missiles from warships in the Caspian Sea.
President Vladimir Putin insists his forces are targeting IS fighters and Russia's defence ministry says the strikes have hit dozens of IS targets in the Homs, Hama, Lattakia and Idlib provinces.
But the US and its allies say many of the strikes have been on areas where IS has little or no presence and independent analysis suggests the Russians may be targeting Syrian opposition groups that pose a threat to President Assad.
Which countries in the US-led coalition are carrying out air strikes?
To date, US aircraft have conducted nearly all of the air strikes undertaken by the coalition in Syria.
In Iraq, other countries have played more of a role - but their contributions are still dwarfed by that of the US. The UK defence secretary Michael Fallon says the RAF has killed about 330 IS fighters in air strikes since 2014.
Militants from abroad
The US Central Intelligence Agency believes IS may have up to 31,000 fighters in the region, many of whom are foreign recruits.
Figures from the London-based International Centre for the Study of Radicalisation and Political Violence (ICSR) and the New York-based Soufan Group show an estimated 20,000 fighters from almost 80 countries have travelled to Syria and Iraq to fight with extremist groups.
The figures suggest that while about a quarter of the foreign fighters are from the West, the majority are from nearby Arab countries, such as Tunisia, Saudi Arabia and Jordan and Morocco.
Iraqi forces recaptured the city of Ramadi, in Anbar province, in December 2015 after weeks of intense fighting. The city had been seized by IS the previous May.
Following the Paris attacks on 13 November 2015, the French launched a series of air strikes on the Syrian city of Raqqa, the de facto capital of the caliphate.
Information about the attacks has been difficult to come by, but the main group monitoring the situation, Raqqa is being slaughtered silently, said the air strikes did not appear to have had much effect.
Tikrit was held for eight months by IS before Shia militias helped recapture the Iraqi city in April. The Iraqi government declared a "magnificent victory" over IS militants after a month-long operation.
Strategic importance of Kobane
Another battleground has been the Kurdish town of Kobane, on the border between Syria and Turkey.
Thousands of residents were forced into Turkey to flee the fighting, while coalition air strikes targeted advancing IS fighters.
After months of fighting, in which about 1,600 people died, US Central Command announced in January 2015 that Kurdish forces controlled 90% of the town.
In June 2015, the Kurdish fighters known as the People's Protection Units (YPG) announced they had seized control of Tal Abyad, a border town to the east, from IS. The move was seen as key to securing the main road south to IS's headquarters in Raqqa.
It also extends the gains by the YPG across the north of the country.
Palmyra ancient ruins
Another key target taken by the militants has been Palmyra in Syria. IS captured the city, which includes a Unesco World Heritage site, in May 2015 and has gone on to destroy a number of its most famous antiquities including its two main temples and three funerary towers.
Syrian government war planes launched a series of attacks on IS positions using weapons supplied by its ally, Russia, in September.
The Islamic State group targeted a number of Iraqi dams during the early stages of their advance, in April 2014, capturing a large facility at Falluja. They went on to take Mosul dam in August 2014, before US air strikes helped force them out later that month.
IS fighters attacked the country's second largest dam at Haditha, but the area was secured by Iraqi forces In September 2014.
Mosul dam has since fallen into disrepair. Fears over security and lack of finance have meant much-needed maintenance has not been carried out and there are fears the dam could collapse, which would cause devastation to communities living along the River Tigris.
IS also gained control of much of the oil infrastructure in Iraq and Syria.
These refineries and the fields supplying them with oil have played a vital role in fuelling IS military units and in generating revenue for the group.
In October 2015, the coalition stepped up its attacks on these locations in Operation Tidal Wave II, in an attempt to damage IS capabilities. Two separate attacks in Syria targeted convoys of oil tankers - after first carrying out a leaflet drop to warn the civilian drivers to get away.
Oil infrastructure across Syria and Iraq
More than four million people have fled abroad to escape the fighting in Syria. Most have gone to Lebanon and Turkey - but a significant number have also gone to Iraq.
Syrian refugees have put pressure on local services and infrastructure in Iraq - which is also having to cope with the return of many Iraqi refugees from Syria.
In addition, the UN estimates there are more than three million Iraqis who have been forced to leave their homes to escape the conflict and are displaced within the country or elsewhere.
Some of those fleeing Syria have attempted to reach Europe, making risky journeys across the Mediterranean from Turkey and Libya. This flow has contributed to a growing migrant and refugee crisis across Europe.