US official: Airstrikes killed 10,000 Islamic State fighters in Iraq and Syria............

A US official said on Thursday that more than 10,000 Islamic State fighters have been killed by American-led airstrikes in Iraq and Syria in nine months, offering a body count for a campaign that has yet to blunt their advance.

Deputy Secretary of State Tony Blinken's figure came after a Paris conference on how to stop the extremists ended without any new strategy to halt their campaign. It also comes months after the Pentagon  dismissed such counts as "simply not a relevant figure" in the fight against the Islamic State group.

Meanwhile, the Islamic State group launched a major attack on the predominantly Kurdish city of Hassakeh in northeastern Syria, according to activists and Syrian state media.

Speaking today to France Inter Radio a day after the Paris conference, Blinken said the airstrikes have been effective.

"We have seen enormous losses for Daesh. More than 10,000 since the beginning of this campaign. That will end up having an effect," Blinken said, using an Arabic acronym for the group. Blinken did not offer any figure for civilian casualties.

In September, the CIA said that Islamic State group has up to 31,500 fighters, meaning that could represent a loss of a third of its forces.

Despite that, the extremists continue to attract more recruits from around the world who come to fight with the group to expand its self-declared caliphate in Syria and Iraq. It's not clear why Blinken offered the figure, as the US military in conflicts since the Vietnam War has been either hesitant or discounted such figures as indicators of success.

Adm John Kirby, a Pentagon spokesman, declined to offer them in January when asked by a reporter.

"The less of these guys that are out there, certainly that's the better, but the goal is to degrade and destroy their capabilities," Kirby said at the time.

He added: "It's simply not a relevant figure." White House spokesman Josh Earnest, later asked about Blinken's figure, said he had "no reason to believe" the number was inaccurate, saying 1,000 Islamic State fighters were killed in the fight for the Syrian border town of Kobani alone.

Meanwhile today, the Islamic State group targeted Hassakeh in an apparent attempt to reverse some of the advances made recently by Kurdish fighters in the northeastern Syrian province.

Kurdish fighters have captured dozens of towns and villages there with the help of US-led airstrikes and are getting close to Tel Abyad, a major Islamic State-held border town near Turkey.