Many countries have said they support a coalition the United States hopes to build to fight Islamic State militants in Iraq and Syria, but most have been vague about any specific role they might play.
Below is a list of some of the key countries that may take part in the anti-IS coalition and where they stand.
France has signaled it will carry out air strikes in Iraq and send special forces to the country to help direct them and to train armed forces. It is providing arms to the Kurds and will send special forces to the country to help direct air strikes and train armed forces.
France has cited legal and military difficulties in intervening in Syria and said it does not want strikes against IS targets there to benefit Syrian President Bashar al-Assad.
France's forces are also stretched, with more than 5,000 troops in West Africa. Its annual overseas defense budget is already almost triple what was originally planned at a time when the government is under severe pressure to cut spending.
Britain has said any strikes in Syria would be complicated. It has not ruled out any military options, but has not explicitly said whether it would take part in air strikes in Iraq. It has delivered aid, given weapons to the Kurds and promised training.
With an election less than nine months away and London on tenterhooks ahead of Thursday's Scottish independence vote, the British government is well aware of public opposition to Britain's role in invading Iraq with the United States in 2003.
British Prime Minister David Cameron is also scarred by an embarrassing parliamentary defeat last summer, when MPs voted against military action in Syria. Members of the government have said they would seek a vote before engaging in any new strikes.
Germany, which broke a post-war pledge not to take part in conflicts by providing weapons to the Kurds, has ruled out air strikes given its historic anti-war stance since the end of World War Two.
Most other European countries have shown little desire to go beyond humanitarian and logistical aid.
Turkey, a NATO member and close U.S. ally that borders both Iraq and Syria, has ruled out taking part in the military effort. It fears any engagement could endanger the more than 40 Turkish nationals being held hostage by IS fighters.
Turkey has backed mainly Sunni rebels in Syria and fears any military action against IS could weaken Assad's foes further. It is also reluctant to strengthen Kurds in Iraq and Syria out of concern that this might stroke demand for independent for independence from its own Kurdish population.
Arab countries have so far not publicly said whether they will take part militarily in the coalition, something the West deems crucial to avoid intervention that is seen as a new Western Crusade in the Middle East.
Arab countries, even those with significant anti-insurgency skills such as Egypt and Jordan, were unlikely to be involved in any ground operation. Washington has said Saudi Arabia will host training for Western-backed Sunni rebels in Syria.
Other Arab states have not been specific, but roles envisaged for them include air strikes, surveillance, providing basing facilities, humanitarian aid and reconstruction.
Most Arab states are already hard pressed to address multiple internal security concerns, and their priority is containing nearby conflicts, defense and border control.