DUBAI, United Arab Emirates – A surge in attacks by the fastest-growing Sunni Muslim militant group has prompted the broadest Arab-U.S. military coalition since the 1991 Gulf War.

Saudi Arabia, the United Arab Emirates, Jordan, Bahrain and Qatar joined the U.S. bombing campaign against the Islamic State in Iraq and the Levant (ISIL) to rein in a group that has rampaged through Syria, threatened to ignite a civil war in Iraq and sought to recruit Saudi militants. Arab backing provides crucial cover for President Obama as he deploys military assets in a region where the United States has been accused of waging war on Islam.

"There's common interest to make sure that these guys are destroyed before they" extend their rule, said Ghanem Nuseibeh, founder of Cornerstone Global Associates, which advises clients on risk in the Middle East.

'Inaction even riskier'

The strikes against the most powerful opposition force in Syria's civil war may benefit President Bashar Assad, a leader whom the United States and its Arab allies want to oust, and expose regional powers to retaliatory attacks by ISIL, an Al-Qaida breakaway group. Still, the group's expansion has made "inaction even riskier for the region," Nuseibeh said.

The mobilization, extending the U.S. campaign of airstrikes beyond Iraq into Syria for the first time, sent a "powerful message to the world," Obama said Tuesday. "The strength of this coalition makes it clear to the world that this is not America's fight alone."

Concerns have grown in Arab states as ISIL declared a caliphate in the heart of the Middle East in an effort to redraw national boundaries set almost a century ago.

Since the 1991 war to force Iraqi soldiers out of Kuwait, in which Arab states also contributed ground troops, U.S. allies have largely shied away from taking part in U.S. military ventures in the region. Most of them publicly opposed the 2003 U.S. invasion of Iraq that toppled Saddam Hussein.

Their involvement in the attacks is militarily symbolic, said Shashank Joshi, senior research fellow at the Royal United Services Institute in London; "it makes a political and strategic difference and shields the U.S. from accusations it's waging some kind of religiously motivated war."

Aggressive policy

The coalition fulfills Obama's pledge to seek partners in the campaign against ISIL. For America's Arab allies, mostly ruled by absolute monarchs and armed with U.S.-made planes and weapons, it's the latest signal they are prepared to forge an aggressive foreign policy against jihadist movements and groups.

The retreat of mainstream Syrian rebels under attack by both Islamist militants and troops loyal to Assad may limit the gains of the campaign.

ISIL will use the coalition attacks as a tool to recruit more fighters, said Andrew Hammond, Middle East policy fellow at the European Council on Foreign Relations. The strikes may also move Arab nations up the list of targets. "Saudi Arabia has appeared in their rhetoric here and there, but now they are putting themselves in the firing line."