U.S. Secretary of State John Kerry is in Turkey as he continues to drum up support among regional allies for a "coordinated military campaign" against the Islamic State fighters. (Reuters)

U.S. and Arab diplomats agreed Thursday to boost military and financial efforts against Islamic State militants in Iraq and Syria, as President Obama’s call to arms against the extremists received mixed reviews in the Middle East and elsewhere.

Secretary of State John F. Kerry and diplomats from across the Middle East coordinated strategies to blunt the militants’ swift march in Iraq and Syria. The Islamic State has proclaimed a caliphate on a third of Syrian and Iraqi territory, functionally erasing the border between the countries in some places.

Saudi Arabia and other Sunni Arab states agreed to expand military help, including opening more bases for airstrike launches and holding training programs for Syrian rebels fighting the Islamists, diplomats said Thursday. The specifics of the effort, however, were not announced.

“This is a moment which is one of those rare opportunities in history, where leaders making the right choices can actually bend the arc of history in the right direction,” Kerry said after a day of talks with officials from Persian Gulf nations including Iraq, along with Egyptian, Jordanian and Lebanese diplomats.

“We believe that we’re all up to this task, and we believe that this is what our citizens are asking of us,” Kerry said. “We believe that we will beat back the evil of ISIL,” he said, using an alternative acronym for the Islamic State, which grew out of an al-Qaeda affiliate and has pursued an even more radical agenda.

A statement issued by the participating nations said they agreed to “do their share in the comprehensive fight against ISIL.” The effort would include, “as appropriate, joining in the many aspects of a coordinated military campaign against ISIL.”

The group also agreed to work toward stopping the flow of foreign fighters across some of their borders and counter the financing of the group from abroad. The United States accuses Qatar and Kuwait, both participants in Thursday’s talks, of not doing enough to stop private donations from their citizens to the militants.

Longtime Saudi Foreign Minister Prince Saud al-Faisal told reporters that the kingdom’s commitment to fighting terrorism is “unlimited,” but he did not provide details.

“Our meeting today was a good opportunity to discuss this phenomena from all different aspects and perspectives, and to go deep in its roots and causes and reflected keenness to come up with a joint vision to combat it through military means, security means and intelligence, as well as economic and financial means, and intellectual means also,” he said.

U.S. officials have said that American military training of Syrian rebels, a feature of the strategy Obama outlined in his prime-time address Wednesday, would take place in Saudi Arabia.

Saudi Arabia is a linchpin of Obama’s strategy, because of its wealth and well-equipped military and because of its role as the spiritual leader among Sunni Arab states.

The fast rise of the Islamic State has unnerved Saudi rulers as well as the authoritarian Sunni governments in Jordan and Egypt, which fear that the militants could march across other borders and inspire further Islamist insurrections.

“Now they have a much deeper appreciation of what ISIL could mean to them, and the Iraq transition has moved ahead reasonably successfully,” a senior State Department official said of Saudi Arabia and other Sunni states. “So I think their thinking has altered on that.”

The official spoke on the condition of anonymity because the additional commitments from Arab governments have not been formally disclosed.

Those same Sunni Arab governments were unwilling to commit major resources to fighting the militants in Iraq when the country was led by Nouri al-Maliki, who left office this week after eight years as prime minister. Maliki was widely considered a Shiite partisan who systematically marginalized Iraq’s Sunni minority.

The Saudi government convened Thursday’s conference after Maliki’s replacement with a Shiite leader viewed as more willing to build an inclusive government.

The Saudis have been critical of what they consider a slow and reluctant U.S. response to the Syrian civil war, a conflict that fueled the growth of the terrorist network. Saudi anger about Obama’s cancellation of planned airstrikes on the Damascus regime last year soured relations for months.

Although Obama insisted Wednesday that he is not leading the United States back into war, the wider campaign he outlined includes airstrikes in Syria supported by the Saudis.

In a front-page editorial, Syria’s state-run al-Thawra newspaper warned against the expansion of airstrikes into Syria — even though President Bashar al-Assad’s government also fears the Islamic State. The editorial said U.S.-directed air campaigns in Syria would trigger “the first sparks of fire” in the region, according to the Associated Press.

Obama’s plan to expand the fight against the Islamic State was broadly welcomed in Iraq on Thursday, although some complained that Washington should have acted faster.

Elsewhere, Obama’s strategies were widely interpreted along political lines: applauded by allies, questioned by some Middle Eastern states and slammed by Russia.

Iran, whose proxy militias in Iraq have joined battles against the Islamic State, described the U.S. coalition as misguided because of the presence of Sunni Arab nations that Tehran views as key rivals.

In Baghdad, Prime Minister Haider al-Abadi’s office issued a statement praising Obama’s objective to “degrade, and ultimately destroy,” the network. The statement also echoed Obama’s call for Iraqi forces to take the lead in the fight, backed by international assistance.

Iraqi political and military leaders have been pushing for decisive U.S. military action since the militants began to claim important territory this year. But Washington was hesitant to provide much support to Maliki and made clear that U.S. airstrikes undertaken this summer were in support of the Iraqi people, not the Baghdad government.

Kerry made an unannounced visit to Iraq on Thursday to congratulate Abadi.

“This is an opportunity for real partnership, and Iraqis realize that we need a proactive relationship with the United States to face the Islamic State,” said Saad al-Muttalibi, a lawmaker from Abadi’s bloc.

However, he added that “the world had expected more from the United States” earlier in the crisis.

The U.S. airstrikes have been aimed at preventing the Islamic State’s advance on the semiautonomous Kurdish region and protecting critical infrastructure, such as a major dam. Iraqi officials say they expect the strikes to be expanded to other parts of the country, including areas near Baghdad that have become flash points.

Morris reported from Baghdad.