Brendan Smialowski, Associated Press
U.S. Secretary of State John Kerry, center, attends a meeting of the Gulf Arab region at King Abdulaziz International Airport in Jiddah, Saudi Arabia, Thursday, Sept. 11, 2014. Kerry sought to pin down Middle Eastern allies gathering in Saudi Arabia on Thursday on what support they are willing to give to the new U.S. plan to beat back the Islamic State group that has seized large swaths of Iraq and Syria.

JIDDAH, Saudi Arabia — Secretary of State John Kerry sought to pin down Middle Eastern allies gathering in Saudi Arabia on Thursday on what support they are willing to give to the new U.S. plan to beat back the Islamic State group that has seized large swaths of Iraq and Syria.

Regional support is seen as key to combatting the spread of the militant group, which has proved so ruthless that even al-Qaida severed ties with it earlier this year. Nearly 40 nations have agreed to contribute to what Kerry predicted will be a worldwide fight to defeat the group.

President Barack Obama on Wednesday laid out a long-term U.S. strategy against the group that would include expanding airstrikes against its fighters in Iraq, launching strikes against them in Syria for the first time and bolstering the Iraqi military and moderate Syrian rebels to allow them to reclaim territory from the militants.

Kerry is aiming to build a coalition in the region behind the fight, with Sunni Arab allies and NATO member Turkey playing leading roles. Already, Saudi Arabia has agreed to open its military bases to train moderate Syrian rebels, according to the United States.

Some Gulf states could help with airstrikes, as the United Arab Emirates and Qatar did in the U.S.-led aerial campaign over Libya in 2011 that helped lead to the ouster of Moammar Gadhafi. Gulf nations could also assist with arms, training, intelligence and logistics.

The coalition-building efforts could be hampered, however, by squabbling among Washington's allies in the region.

For example, Saudi Arabia, the Emirates and Egypt are at odds with Qatar and Turkey because of the latter's support for the Muslim Brotherhood and other Islamist groups in the region.

In an opinion piece in The Wall Street Journal this week, the Emirates' ambassador to Washington called for a coordinated and sustained international effort to combat Islamic extremists. Yousef al-Otaiba said his country is prepared to join an international effort to fight the Islamic State. But he called for a broader fight against extremists in the region, including al-Qaida's Nusra Front branch in Syria and other groups in Yemen and North Africa.

Arriving in Saudi Arabia's Red Sea coastal city of Jiddah, Kerry held talks with his Saudi and Bahraini counterparts as diplomats from across the region trickled into an ornate conference center at the city's airport.

Kerry is expected to meet later in the day with officials from across the Gulf Arab region as well as envoys from Egypt, Jordan, Lebanon, Iraq and Turkey to press his case for greater regional support.

The U.S. already has launched more than 150 airstrikes against militants in Iraq over the past month, and has sent military advisers and millions of dollars in humanitarian aid, including an additional $48 million announced Wednesday.

Saudi Foreign Minister Prince Saud al-Faisal, using a cane, walked to greet Kerry at the mouth of a jetway as he disembarked from his Air Force plane. The two met shared a brief welcoming coffee ceremony over their private discussions.

Kerry later sat down with Bahraini Foreign Minister Khalid bin Ahmed Al Khalifa, whose tiny island nation hosts the U.S. Navy's Fifth Fleet. An American aircraft carrier assigned to the fleet has been carrying out airstrikes against militants in Iraq.

The Mideast diplomatic push comes ahead of a conference set for Monday in Paris on how to stabilize Iraq. That meeting will include officials from the U.S., Britain, France, Russia and China, and could also include other nations — possibly even Iran.

Schreck reported from Dubai, United Arab Emirates. Follow Lara Jakes on Twitter at: https://twitter.com/larajakesAP and Adam Schreck at https://www.twitter.com/adamschreck .