Defence chiefs from the United States, France, Britain, Australia and three other nations meet in Paris on Wednesday to examine ways to accelerate gains against Islamic State.
The talks will include potentially ramping up the number of police and army trainers.
US Defence Secretary Ash Carter described the gathering as a chance for face-to-face talks among the core contributors in the US-led coalition, which also includes Germany, Italy and the Netherlands.
"I'll be soliciting their views and describing to them my thoughts about how we can accelerate the campaign, including the variety of capabilities, military capabilities, that will be required," Carter said, predicting increases in the numbers of trainers in the months ahead.
That would include police who can help hold territory seized from Islamic State.
France was the first country to join US-led air strikes in Iraq. Since the Paris attacks by Islamic State militants in November, President Francois Hollande has stepped up French aerial operations against Islamic State, including in Syria, contributing about 20 percent of coalition strikes.
A French defence ministry official, speaking on condition of anonymity, said the coalition would discuss ways to broadly intensify the effort.
"It's not just about adding more planes, but also trainers to accelerate the speed with which local forces can retake territory against Daesh," the official said, using a colloquial term to describe Islamic State.
In a telling sign, no Arab states from the region are joining the gathering of top contributors to the campaign. A senior US official acknowledged that many Arab allies have been occupied with the Saudi Arabian-led campaign against Houthi militants in Yemen.
Carter said he would be discussing with his allies how to draw a greater contribution from the Sunni Arabs, many of whom view the US-backed, Shi'ite-led government in Baghdad with suspicion. They also accuse the United States of not moving firmly enough against Syrian President Bashar al-Assad.
Officials said a key focus would be finding ways to increase contributions from other nations outside the "core contributors" to the coalition effort. That could include trainers.