More than 50 countries, including more than a dozen western ones, are taking part one way or another in a coalition to defeat the Islamic State (IS) organization in Iraq and Syria, according to US officials.
About 30 nations agreed in mid-September to provide Iraq with all necessary backing, including military means.
The United States has been helped by five Arab "partner nations" -- Bahrain, Jordan, Qatar, Saudi Arabia and the United Arab Emirates -- with air strikes in Syria.
Only the United States and France have carried out strikes in neighboring Iraq so far, though British lawmakers voted on Friday to approve joining the campaign.
UNITED STATES: At the core of the coalition, the United States began hitting IS positions in Iraq on August 8. After initially focusing on areas in northern and western Iraq, the strikes were expanded to targets near Baghdad. Almost 200 strikes have been carried out to date.
On September 23, the US expanded the scope of its operations to Syria, with backing from Gulf governments, and has since hit oil installations controlled by the IS to degrade the group's key source of revenue.
US President Barack Obama has called for countries worldwide to unite and "destroy" the IS in Iraq and Syria, but says he is determined not to put American combat troops on the ground.
Some 1,600 US soldiers have nonetheless been deployed to Iraq to reinforce Iraqi forces with equipment, training and information.
The US Congress has also approved a plan to train and equip moderate Syrian rebel units.
FRANCE: French warplanes have conducted two rounds of air strikes in Iraq since the country joined the US air campaign on September 18.
France has also delivered arms to Iraqi Kurdish fighters and provided humanitarian aid, in particular to the region around Arbil.
BRITAIN: Lawmakers in Britain's House of Commons voted overwhelmingly in favor of joining US-led air strikes on IS targets in Iraq.
London has already provided heavy machine guns and munitions to Kurdish fighters on top of previous military deliveries.
SAUDI ARABIA, UNITED ARAB EMIRATES: Saudi Arabia and the UAE are leading the charge by Gulf monarchies.
The two countries have played a major role in recent strikes against IS targets in Syria.
According to the Pentagon, 10 of 16 planes that hit oil refineries controlled by militant group were from Saudi Arabia and the UAE and the two countries accounted for 80 percent of the ordnance used.
Prior to that, Saudi Arabia had hosted moderate Syrian rebels for training and provided equipment for them.
BAHRAIN: Host to the US Fifth Fleet, Bahrain has confirmed having taken part along with other Gulf monarchies in air strikes against IS jihadists in Syria.
JORDAN: A neighbor of both Iraq and Syria, the kingdom has acknowledged participating actively in initial strikes on Syrian soil.
King Abdullah II has said his country "is at the forefront" of efforts to form "a collective strategy to contain and defeat" groups such as the IS.
QATAR: Qatar has remained discreet regarding its level of participation in anti-IS strikes. It has nonetheless allowed the US to use the Al-Udeid airbase for airborne units of Centcom, the US command center for the Middle East and Central Asia.
On Friday, the Emir of Qatar denied that his country was financing extremist groups and affirmed his unwavering long-term commitment to the coalition.
KUWAIT: Hosts US military facilities.
ALBANIA, CZECH REPUBLIC, DENMARK, ESTONIA, POLAND: These countries have delivered military equipment and munitions to forces fighting the IS.
AUSTRALIA: Has deployed 600 soldiers to the UAE and has delivered military equipment to Iraqi Kurds.
BELGIUM: Providing six F-16 combat jets to the coalition force following parliamentary approval, with stipulation they can only intervene in Iraq.
CANADA: Has sent 69 special forces soldiers, as well as military equipment, to Iraq. It has also transported military equipment from Albania and the Czech Republic.
DENMARK: The Danish prime minister said Denmark would send seven F-16 jets to Iraq.
GERMANY: Has delivered arms and is training Kurdish fighters. Berlin also plans to send around 40 soldiers to Iraq.
ITALY: Has supplied light weapons.
TURKEY: President Recep Tayyip Erdogan signalled that Turkey would take a more active role in the international coalition following the release of Turkish hostages held by the jihadists.