WASHINGTON - President Obama and top military commanders meet Tuesday afternoon with the defense ministers from more than 20 countries that have joined the fight against the Islamic State in Iraq and Syria (ISIS, or ISIL).

The meeting comes as the White House tries to tout progress in the U.S.-led campaign against the militants, while also girding the public for a military effort that could extend well beyond Obama's presidency. Administration officials said the meeting would focus on military strategy and ways to bolster the campaign to counter the extremists.

In a Monday meeting with the defense ministers of the Americas in Arequipa, Peru, Defense Secretary Chuck Hagel said the group would be "defining specific contributions that these nations will make."

CBS News National Security Correspondent David Martin reports that the U.S. will be pressing Arab nations at this meeting to deploy their special forces inside Syria.

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Defense chiefs attending include the Arab nations that have joined the U.S. in conducting airstrikes against the group, like Saudi Arabia and the United Arab Emirates, as well as representatives from European partners Britain and France and Turkey, a key NATO ally that neighbors both Syria and Iraq.

The U.S. has pushed the Turkish government to expand its role in fighting ISIS, as ISIS threatens to overrun the town of Kobani that sits on the Turkey-Syria border.

On Sunday, American officials said Turkey will allow U.S. and coalition forces use its bases for operations against ISIS, but on Monday Turkish officials denied that it had reached such a deal with the U.S. and instead said the two countries would hold deeper talks in the coming days.

"I am optimistic about progress that we are making with the Turks as they ... further define their role in the coalition against ISIL," Hagel said Monday.

CBS News Foreign Correspondent Holly Williams reports the terror group is gaining more ground in Syria and Iraq, even after weeks of airstrikes by the U.S. and other countries. ISIS militants have captured an Iraqi army camp in Hit, west of Baghdad, as the Islamic extremists edge closer to total control of Iraq's Anbar Province.

Iraqi government soldiers were forced to withdraw despite U.S. airstrikes aimed at pushing ISIS back.