Washington: The United States plans to strike the Islamic State group in its Syrian strongholds and could send military advisors into combat alongside Iraqi troops, American commanders said on Tuesday.
Military leaders warned of a further escalation in their battle against the jihadists just as two branches of the rival Al-Qaeda group called for a united front against the war coalition Washington is building.
US warplanes have been targeting IS jihadists in northern Iraq since August 8, and in recent days hit the militants southwest of Baghdad for the first time, in a significant expansion of the campaign.
Meanwhile, Defence Secretary Chuck Hagel told US lawmakers that plans are being laid to hit targets in Syria, where the IS group is holding hostages and has a stronghold in the city of Raqa.
"This plan includes targeted actions against ISIL safe havens in Syria, including its command and control, logistics capabilities, and infrastructure," Hagel told the Senate Armed Services Committee.
But the US military's top-ranking officer, General Martin Dempsey, told the same hearing the bombing would not match the huge raids that accompanied the start of the 2003 US-led invasion of Iraq.
"This will not look like 'shock and awe' because that is not how ISIL is organised, but it will be persistent and sustainable," Dempsey said, using the term Washington used for its 2003 bombardment.
Dempsey also went further that any US official has gone before in admitting that the military advisors that President Barack Obama has dispatched to bolster Iraqi forces could get involved in combat.
Obama's administration has insisted that his action against the IS extremists is not the start of another US ground war in the Middle East, and that there will be no large-scale American invasion.
But nearly 300 US military advisers are already working with Iraqi government forces, 300 more are on their way and Dempsey refused to rule out their providing "close combat advising."