The U.S.-led coalition attacking Islamic State in Iraq and Syria now boasts dozens of nations although President Barack Obama has yet to secure UN Security Council authorization and the legality of the entire campaign remains murky.
In Iraq, the attacks have the legitimacy conferred by being formally at the request of the Baghdad government. In Syria, where a civil war is raging, there's no request from Bashar al-Assad's regime – which Mr. Obama still wants toppled – or the United Nations Security Council. That's why some nations, notably Britain, will bomb Islamic State jihadis in Iraq, but not in Syria.
As in the U.S.-led air wars in Kosovo in 1999 and Libya in 2011, the overwhelming majority of the attacks will be made by U.S. warplanes. Only a handful of nations, now including Canada, Australia, Britain, Denmark and France, as well as Jordan, Saudi Arabia, and the United Arab Emirates have committed combat aircraft.
The rest of the coalition ranges from Albania, shipping 32,000 surplus Cold War-era artillery shells and 15,000 hand grenades, to Luxembourg, which is sending 3,300 tents and 18,000 kitchen sets, to the Netherlands, which is providing 1,000 helmets for Kurdish peshmergas, to Israel, where Prime Minister Benjamin Netanyahu has to "play our part in this continued effort."
"The fight will not be easy. There will be ebb and flow on the battlefield," retired General John Allen said in Baghdad. "This will take time and requires patience."
This is a partial list of the public contributions of individual countries to the effort against Islamic State militants. Some countries have not made public their contributions, so this list does not reflect every element of the international response.
Albania: Sending large quantities of weapons to help Kurdish fighters, including up to 22 million AK47 rifle rounds and 32,000 artillery shells.
Arab League: The Arab League has endorsed a UN Security Council resolution passed last month calling on member states to "act to suppress the flow of foreign fighters, financing and other support to Islamist extremist groups in Iraq and Syria."
Australia: Two hundred special forces troops will be deployed and aircraft will join U.S.-led coalition strikes.
Belgium: Sending 13 tonnes of humanitarian aid to be distributed to refugees in the Kurdistan region.
Bulgaria: Bulgaria has offered military assistance in the form of munitions and humanitarian aid.
Czech Republic: Delivering $2-million worth of ammunition for Kalashnikov assault rifles and machine guns, as well as hand grenades and ammunition for rocket-propelled grenades to the Kurdish forces in northern Iraq.
Denmark: Sending a C-130J transport aircraft to support efforts to combat the terrorist organization Islamic State in Iraq.
Estonia: Donating one million machine gun cartridges and providing humanitarian assistance.
France: France has carried out two rounds of air strikes in Iraq and just under 1,000 soldiers are based in the Gulf.
Germany: Providing arms and weapons training to Kurdish fighters as well as emergency aid. Germany has said it will provide the Kurdish fighters with 16,000 assault rifles, hundreds of anti-tank weapons and armoured vehicles.
Hungary: Providing humanitarian assistance and sending several million cartridges, and thousands of mines and armour-piercing shells.
Italy: Has pledged to provide refuelling planes to support air strikes and weaponry to support Kurdish fighters as well as humanitarian assistance.
The Netherlands: Providing Kurdish forces with helmets and bullet-proof vests and has agreed to transport arms and ammunition as well as humanitarian aid.
Norway: Providing a C-130J Super Hercules transport aircraft to deliver humanitarian aid.
Turkey: Turkey's parliament has authorized military action against Islamic State militants that will allow the country's military to leave its borders to go after terror groups, but also allow foreign troops to launch operations from Turkey. The authorization takes effect Saturday.
United Kingdom: Britain conducted its first air strikes this week in Iraq after British parliament approved a motion to join the U.S.-led military campaign. Britain is also providing equipment directly to Kurdish forces.
With reports from Reuters and the Associated Press