Islamic State battle could take years, Pentagon says

The fight against jihadist group Islamic State (IS) will take years, a US military spokesman has told the BBC.

Rear Admiral John Kirby also said that US-led air strikes against IS in Syria had disrupted the group's capabilities.

The remark came as President Barack Obama thanked Arab states for help and Secretary of State John Kerry said more than 50 nations had agreed to fight IS.

IS has seized large areas of Syria and Iraq, and the US has launched nearly 200 air strikes in Iraq since August.

Monday's strikes however expanded the anti-IS campaign across the border into Syria for the first time.

Activists say at least 70 IS militants and 50 other al-Qaeda-linked fighters were killed in the strikes.

Speaking in Washington, Rear Adm John Kirby said the air strikes in Syria had successfully degraded IS's capabilities.

"We think we have hit what we were aiming at," he said.

However, IS was good at adapting and reacting to changes, he said, adding that the group presented a "serious threat" that would not be eliminated "within days or months."

"It's going to take a serious effort by all involved. We do believe that we're talking about years here."

Meanwhile, Mr Kerry told reporters that more than 50 countries had agreed to join efforts to fight IS.

"We will not allow these terrorists to find a safe haven anywhere," he said