From left, Egypt's Foreign Minister Sameh Shoukry, Kuwait's Foreign Minister Sabah Al-Khalid al-Sabah, Saudi Foreign Minister Prince Saud al-Faisal, U.S. Secretary of State John Kerry, Oman's Foreign Minister Yussef bin Alawi bin Abdullah, Bahrain's Foreign Minister Sheikh Khaled bin Ahmed al-Khalifa and Lebanon's Foreign Minister Gebran Bassil met Thursday in a U.S. diplomatic effort to secure support from nations across the globe. (Brendan Smialowski/Pool/Reuters)

The coalition that is likely to partner with the United States to fight the extremist group known as the Islamic State began to take shape Thursday and could include a global mixed bag of nations, including Arab states, European allies and long-time U.S. adversaries such as Iran and China.

In his speech to the nation on Wednesday, President Obama promised the United States would “lead a broad coalition to roll back this terrorist threat” but insisted no participants would be required to put combat troops on the ground.

Since then, diplomatic efforts have been ongoing to secure support from nations across the globe. On Thursday, Secretary of State John Kerry visited Saudi Arabia to gather support from Arab states. He spoke with envoys from Egypt, Turkey, Jordan, Lebanon, Qatar, Kuwait, Bahrain, Oman, the United Arab Emirates and Iraq in hope of cementing the coalition. Many of these countries are expected to provide money, military resources and diplomatic support in the battle against the Islamic State.

In Europe, there have been mixed messages from some of the potential allies. At the NATO summit in Wales last week, Defense Secretary Chuck Hagel suggested a “core coalition” of Western allies who would join the fight — Britain, France, Australia, Canada, Germany, Turkey, Italy, Poland and Denmark.

Although the White House has revealed few other details, a senior administration official said “we are very confident that this will be a broad-based coalition with countries from the Arab world, from Europe, but also other key allies around the globe.”

President Obama said the U.S. will work with a "broad coalition" of foreign partners to combat the Islamic State in his public address on Wednesday, Sept. 10, 2014. (The Associated Press)

Membership of this coalition appears to be wide open, with the United States actively appealing to nations normally regarded as adversaries. During a trip to China, National Security Advisor Susan Rice urged Beijing to assist in the fight against the Islamic State. There is also a possibility that Iran will play a part in the international coalition, but it is unknown if and how the United States would work with Tehran.

Kathleen H. Hicks, senior vice president at the Centre for Strategic and International Studies and a former official in the Department of Defense, says she believes the Obama administration is taking the coalition building very seriously.

“It’s been critical to get Saudi Arabia on board, particularly in such a big way,” she said. “They have a lot of sway in the Gulf, particularly with the vital Sunni states in the region.”

Hicks also says the involvement of the French is key for building credibility.

“In Europe, France is important because they have committed to airstrikes in Iraq, which means the United States is not the only country conducting airstrikes. It is noticeable that none of the other allies are agreeing to airstrikes in Syria,” she says.

Even the more reticent allies of the United States have been hawkish in condemning Islamic State, but the level of support on offer has been mixed.

German Chancellor Angela Merkel estimated last month there are around 2,000 Islamic State fighters from Europe, 400 of which are from Germany. “We can’t just say it has nothing to do with us. We are implicated,” she said. Although Germany usually shies away from foreign interventions, Merkel said her country will provide weapons and ammunition to Kurdish fighters in Northern Iraq.

However, the German Foreign Minister Frank-Walter Steinmeier denied Germany will participate in any airstrikes. “Neither were we asked to do this, nor will we do it,” he said Thursday.

French President François Hollande has been enthusiastic about his nation’s involvement in the mission. “Are we going to participate in a coalition at the request of Iraqi authorities, in the respect of international law, to fight this terrorist group? The response is yes,” he said at the NATO conference last week.

Canadian Prime Minister Stephen Harper has also condemned Islamic State while his Foreign Affairs Minister John Baird has said “Canada will not stand idly by while ISIL continues to murder innocent civilians, including members of ethnic and religious minorities.”

Australia’s Tony Abbott has welcomed Obama’s “measured and careful response,” describing Islamic State as a “hideous movement.” Abbott has not ruled out some military involvement, but like all of the other partners in the coalition, he said Australia will not put boots on the ground.

Obama has worked particularly hard to bring one key member of the coalition onboard. During his visit to Wales last week, Obama and British Prime Minister David Cameron co-authored an op-ed in the Times of London, stating “[we] will not waver in our determination to confront ISIL.”

British Foreign Secretary Philip Hammond was less enthusiastic. On Thursday, he said, “Let me be clear: Britain will not be taking part in any airstrikes in Syria.”

A few hours later, he was overruled by Cameron. “In terms of air power, the prime minister has not ruled anything out, and that is the position,” his spokesman said.