The US-led coalition against the militant Islamic State group in Iraq and Syria groups more than 60 countries, of which a dozen are taking part in air strikes.
Washington is carrying out its strikes in Syria with the help of Arab allies - Bahrain, Jordan, Saudi Arabia and Qatar.
In Iraq it has the active support of seven Western countries - Australia, Belgium, Britain, Canada, Denmark, France and the Netherlands.
The coalition has since August carried out 2,000 air strikes, US Secretary of State John Kerry said on February 8.
While excluding the deployment of ground troops, coalition countries have also sent more than 1,000 military trainers to work with Iraqi forces.
Below are contributions from the main coalition members:
UNITED STATES: The US started to bombard IS positions in Iraq on August 8, 2014 and extended operations to Syria on September 23.
The 2016 budget earmarks $8.8 billion for the fight against IS.
Around 1,830 American soldiers are currently deployed in Iraq to assist its armed forces in equipment, training and intelligence.
AUSTRALIA: Canberra sent eight RAAF F/A18s to the United Arab Emirates (UAE) to take part in air strikes. On October 19, it announced sending 200 members of its special forces as advisers in Iraq. It has also sent military equipment and humanitarian aid to Iraqi Kurds.
BELGIUM: Brussels has committed six F-16 fighter jets and 120 troops, based in Jordan.
BRITAIN: London has deployed eight Tornado fighter bombers and started to conduct air strikes on September 30.
The government announced in October the redeployment from Afghanistan to Iraq of several of its Reaper drones.
In late 2014, London announced the deployment of several hundred extra British soldiers to Kurdish zones of northern Iraq and to near Baghdad to train Iraq's infantry and help them fight against improvised explosive devices.
London has delivered machine-guns and ammunition to Iraqi Kurdish forces.
CANADA: Ottawa has deployed six F-18 fighter jets to Kuwait to take part in strikes in Iraq and officially deployed 69 members of its special forces to train Iraqi and Kurdish forces.
In the first confirmed ground battle between Western troops and IS, Canadian special forces in January exchanged gunfire with jihadist fighters in Iraq.
FRANCE: Paris joined air strikes in Iraq on September 19, 2014. On Monday, it deployed the Charles De Gaulle aircraft carrier in the Gulf to work alongside the USS Carl Vinson.
The ship carries 12 Rafale and nine Super Etendard fighters, in addition to nine Rafales in the UAE and six Mirage fighters in Jordan operating over Iraq, along with a maritime patrol and a refuelling aircraft.
The Charles de Gaulle strike group includes an attack submarine, a French anti-aircraft frigate and the HMS Kent, a British anti-submarine frigate. A total of 2,700 sailors are involved, including 2,000 on the carrier itself.
NETHERLANDS: Apart from six F-16 fighter jets based in Jordan for missions in Iraq, and two others in reserve, The Hague on October 5 announced it was deploying 250 soldiers in Iraq as trainers.
SAUDI ARABIA: The leader of the Gulf monarchies has been taking part since September in air strikes on IS positions in Syria and has accepted moderate Syrian rebels for training and equipping.
UNITED ARAB EMIRATES: Abu Dhabi resumed air strikes on February 10 in Syria, having suspending the raids after IS captured a Jordanian pilot in December.
On February 7, the UAE ordered a squadron of F-16 warplanes to be stationed in Jordan to support it in strikes against the IS.
BAHRAIN: Home of the US Fifth Fleet, Manama has taken part from the start in air strikes in Syria and on February 16 announced the deployment of fighter jets in Jordan.
JORDAN: A neighbour of both Iraq and Syria, the kingdom has also taken part in strikes in Syria since the outset.
It stepped up raids after the February 3 announcement of the execution of Jordanian pilot Maaz al-Kassasbeh, burned alive by IS which captured him after his plane crashed.
On February 5, Jordan also joined air strikes on Iraq.
QATAR: Doha has supported air strikes in Syria, making available its Udeid air base, home of Centcom, the US central military command for the Middle East and central Asia.
TURKEY: Concerned by Kurdish activities, it joined the coalition on October 2 but has declined to take military action. After months of difficult negotiations, it signed a February 19 accord with the US to train and equip moderate Syrian rebels.
The US government hopes the programme can start by late March and the first trained rebel forces become operational by year's end.
Other countries, including the Czech Republic, Germany, Italy, Norway and Spain, have either sent hundreds of soldiers to train Iraqi or Kurdish forces, or hosted training. Others have delivered arms and ammunition.