Defeating Islamic State will take years, Secretary of State John Kerry admits

A global fight against Islamic State militants will likely take years to fully succeed, but nations are prepared to engage "for as long as it takes" to defeat the bloody insurgency, US Secretary of State John Kerry said yesterday.

Nearly a year after the Islamic State overran key cities in western Iraq, diplomats from more than 60 countries and international organisations gathered in Brussels to plot a way forward against what has since become one of the world's worst terror threats.

The mostly Sunni Muslim insurgency now stretches across much of northern Iraq and Syria, and has attracted thousands of foreign fighters from around the world, including Asia and Europe. Its elusive leadership is flush with financial support from illicit donations and black-market oil sales.

"We recognise the hard work that remains to be done," Kerry told the gathering at Nato headquarters, which hosted what was the largest meeting of foreign ministers to discuss Islamic State. "Our commitment will be measured most likely in years, but our efforts are already having a significant impact."

"We will engage in this campaign for as long as it takes to prevail," the top US diplomat said.

Kerry also met privately with Iraqi Prime Minister Haidar al-Abadi, who asked for "a lot of support to be able to crush Daesh" - the Arabic acronym for the Islamic State. "I think we're the only country in the Middle East who is really fighting Daesh on the ground," he said.

Since August 8 - nearly two months after militants seized control of Mosul, Iraq's second-largest city - the US and allies have launched more than 1,000 air strikes against Islamic State in Iraq and Syria. Kerry said the attacks had greatly hampered the insurgency, and cited training missions and equipment being supplied by other nations that had joined the coalition since it was created less than three months ago.