Islamic State 'neither a state nor truly Islamic': John Kerry

Washington: US Secretary of State John Kerry Monday described the feared Islamic State group as neither "a state nor truly Islamic", adding that America takes seriously the "unacceptable threat" posed by the terrorist organisation.

"The group calling itself the Islamic State is, in fact, neither a state nor truly Islamic. It is an adversary without a uniform, without any support by any government, and offering nothing in terms of coherent social or political programme," Kerry told a Washington audience.

"But it is a foe we take very seriously, in part because the dysfunction of some governments in the region has enabled these killers to seize control of more land and more resources than Al-Qaida ever had on the best day of its existence," he said.

The top US diplomat said the brutal militant outfit "has stolen vast quantities of weapons and money. It is attempting to recruit the fanatical and misguided in dozens of countries ... In the process, it has become a threat to America's core interests."

The Islamic State, also known by its acronym ISIS or ISIL, has gained sway over a vast portion of Iraq's midsection, including Mosul -- the second largest city, and Syria. It is widely feared for its brutal abuses.

IS emerged from Al-Qaeda affiliate Islamic State of Iraq (ISI), and announced its presence in Syria in April 2013.

"The terrorists pose an unacceptable danger to American personnel and facilities in Iraq and elsewhere. And their aggression adds to the terrible burdens placed upon our friends and allies in Turkey, Jordan, Lebanon," he said.

Kerry said if the extremist organisation remains unchecked it could become "a rallying point for the alienated and disaffected on every continent, spawning imitators and spurring individuals in far flung places to commit stupid, destructive, suicidal acts."

"As the Islamic State or (the) ISIL has shown, by its actions, its desire is to impose its will over as many people and as much territory as it can. But unlike some extremist groups, it is relatively well- organised, disciplined, even," he added.

It released a video yesterday, showing the beaheading of US aid worker Peter Kassig and that of 18 men described as Syrian military personnel.

"Their strategy is based entirely on fear. And many of their captives are executed, some beheaded, some buried alive, some crucified. Others are given a choice to pledge allegiance or die. Children are tortured, killed, or forced to take up arms," he said.

Referring to the US-led global coalition which has carried out aerial strikes against IS, Kerry said overall the campaign has begun to have a significant impact.

"The momentum that ISIL built up during the summer has dissipated. It continues, yes, to commit terrible crimes. But it has also been forces to relinquish bases, abandon training sites, alter its mode of communications, disburse personnel, and stop the use of large convoys," he said.