The language stood out to some foreign policy observers, in part because a number of Obama administration officials have reservations about the potentially destabilizing effect of creating a large standing force dominated by mostly Sunni Arab nations.

The statement distributed by the White House following Thursday’s summit of Arab leaders at Camp David marked President Obama’s first clear public gesture of encouragement for an Arab League proposal to create a force numbering in the tens of thousands.

The White House announced the creation of a new “senior working group” between Washington and the Arab capitals that will “pursue the development of rapid response capabilities” which could handle counter-terrorism missions.

The statement referred to an Arab League plan announced at a March meeting of the regional body. Arab officials have said the force could number between 20,000 and 40,000 troops and would be modeled after a NATO quick-response force comprised of about 30,000 soldiers.

Some analysts said the language amounted to the only real advance at a summit whose official statement mostly wound up reiterating policies already in effect.

“If there is one tangible takeaway, and something potentially new, this is it,” said Matthew Levitt, a counter-terrorism expert at the Washington Institute for Near East Policy.

Levitt and others cautioned that the White House’s language was vague and committed the administration to no new action.

A senior administration official declined to offer more detail on what role the U.S. might play in standing up an Arab force, suggesting that Arab governments would have to act first.

“The discussions are ongoing among Arab states to determine the precise structure and operational mandate of the proposed force, so we will wait to see what shape it takes,” the official said.

The concept has surfaced in the past to no avail, but recently it has taken on new life with the rise of militant groups like the Islamic State in Iraq and the Levant, as well as growing Arab alarm over Iran’s regional influence.

To be effective, an Arab force would likely require significant U.S. training, intelligence and equipment.

But the concept poses vexing questions for Obama’s national security team.

On the one hand, Obama longs to disentangle America’s military from the Middle East. Outsourcing missions like counter-terrorism that draw in U.S. forces would make that disentanglement easier. But the U.S. is also wary of ceding too much influence in a strategically vital, oil-rich region.

And an Arab force could bring more instability and violence to the already-roiling Middle East, with unpredictable consequences.

The composition and leadership of any Arab military force is likely to be dominated by Sunni Arab nations, like Egypt and Saudi Arabia, who see themselves in a war not just with radical Sunni groups like al Qaeda and ISIL — but also with Shiite Iran and its proxies.

The recent Saudi-led bombing campaign against Yemen’s Houthi rebels could be a cautionary tale. Some U.S. officials believe that Saudi Arabia has overreacted to Iranian support for the Houthis and worry the air campaign has caused high civilian casualties and a humanitarian disaster. Even as the U.S. provides intelligence and logistical support for the Yemen campaign, Obama officials are expressing strong reservations to the Saudis about their conduct.

Yemen is just one example of a more aggressive approach by top Arab states across their borders. Last August, Egypt and the United Arab Emirates mounted joint airstrikes against militants in Libya. And in February, Egypt struck again after terrorists claiming ties to ISIL beheaded 22 Egyptian Christians in its North African neighbor.

Several Arab states, including Saudi Arabia and Egypt, have also joined the U.S.-led coalition against ISIL in Iraq and Syria.

But even as they cooperate, some members of the anti-ISIL coalition are pressing the U.S. to take stronger action against their enemies in the region.

Obama officials say that Egypt’s ruler, Gen. Abdel Fattah el-Sisi has urged Washington to expand the ISIL campaign beyond Iraq and Syria into Libya. Sisi has complained that America only cares about threats to its direct interests, and should repay Arab states for their cooperation against ISIL by going after more localized threats to Arab capitals.

Quickly hitting ISIL operatives in Libya would be a natural mission for a pan-Arab force — if one can be constituted effectively.

Many analysts doubt it.

“It’s difficult for these countries to work together in a systematic way,” said Ray Takeyh, a Middle East expert at the Council on Foreign Relations. “When the regional states with their limited capabilities interfere in a civil war, they usually make things worse – they usually make things worse for themselves, too.”

The Arab states have long been riven with mutual suspicion. Last March, Saudi Arabia, Bahrain and the UAE withdrew their ambassadors from Qatar to protest Doha’s support for groups like the Muslim Brotherhood, which those monarchies consider terrorist actors.

Bilal Saab, a senior fellow at the Atlantic Council, said any Arab force could be hampered by disputes over what missions to prioritize, not to mention serious technological challenges in integrating their military efforts. “It’s going to take a bit more than desire to make this work,” Saab said.

But Fahad Nazer, formerly a political analyst at the Saudi embassy in Washington, said recent events have put wind in the idea’s sails.

“I think that the Saudi military campaign in Yemen, which does include a fair number of Arab countries, has also made the notion of collective Arab military action seem more realistic than a mere pipe dream,” Nazer said.