The air campaign against the Islamic State group has made progress in degrading the jihadist organisation but will not be enough without local boots on the ground, the US air force secretary said on Tuesday.

The comments from Deborah Lee James come just days after Pentagon chief Ashton Carter raised the possibility of deploying additional US special forces personnel to Syria if more partners can be found among local forces on the ground.

"Air power is extremely important. It can do a lot but it can't do everything," James said.

"Ultimately it cannot occupy territory and very importantly it cannot govern territory," she told reporters at the Dubai Airshow.

"This is where we need to have boots on the ground. We do need to have ground forces in this campaign."

James cited the "Iraqi army, the Free Syrians and the Kurds" as forces to support in the fight against IS.

A US-led coalition has been carrying out air strikes against IS in Iraq and Syria for more than a year in a campaign that has seen the jihadists lose some territory but also make new gains.

The White House announced on October 30 that US President Barack Obama had authorised the first sustained deployment of "fewer than 50" special force personnel to Syria, reversing a longstanding refusal to put US boots on the ground.

And in an interview on Sunday, the Pentagon chief said that more US troops could "absolutely" be deployed to Syria if Washington identifies more "capable local forces" as partners in the fight against IS.

While US troops are believed to have carried out covert missions in Syria before, they had not previously been deployed there on a continuous basis.

Gulf air strikes on IS down due to Yemen conflict: US general
Dubai (AFP) Nov 10, 2015 –

Air strikes by Gulf Arab members of the US-led coalition fighting the Islamic State group in Syria have diminished since they launched an air war against Yemeni rebels in March, a US general said Tuesday.

Bahrain, Saudi Arabia and the United Arab Emirates have carried out air strikes against IS in Syria but the three Gulf Cooperation Council members are also involved in an air and ground campaign in Yemen in support of exiled President Abedrabbo Mansour Hadi.

"There is a mix of GCC that is participating in Yemen as well as in the operations in Iraq and Syria," said US Air Forces Central Command chief Lieutenant General Charles Q. Brown.

"Less so since March because they've been occupied with the Yemen operation," he told reporters at the Dubai Airshow.

Washington has been leading mainly Western allies in carrying out air strikes against IS in Iraq since August last year.

In September last year, it launched air strikes against IS in Syria with the support of mainly Arab allies.

In September this year, Russia launched its own separate bombing campaign in Syria in support of its ally President Bashar al-Assad.