Live Blog: War against Islamic State

• Obama admits US underestimated IS threat
• UK PM underlines need for ground troops to fight IS
• Syrian Kurds continue to stream into Turkey
• US-led airstrikes destroy three makeshift oil refineries in Syria, according to monitoring group
• IS tries to regain Kobani near the Turkish-Syrian border

President Barack Obama admitted Sunday that the United States had underestimated the opportunity that a collapsing Syria would provide for militants to regroup and stage a sudden comeback.

Speaking to CBS News, the president said that former Al-Qaeda fighters driven from Iraq by US and local forces had been able to gather in Syria to form the newly dangerous Islamic State group.

"I think our head of the intelligence community, Jim Clapper, has acknowledged that they underestimated what had been taking place in Syria," he said, referring to his director of national intelligence.

Asked whether Washington has also overestimated the ability or will of Iraq's US-trained military to fight the militants on its own, Obama said: "That's true. That's absolutely true." 

According to the Observatory, strikes in Syria since 23 September have killed 141 militants, including 129 foreign fighters, of whom 84 were IS-affiliated.

The international coalition against the Islamic State will fail without Iran’s support, former President Hashemi Rafsanjani has warned.

Speaking in Tehran on Sunday, Rafsanjani said: "The airstrikes will not destroy this organization and no solution can be found for terrorism in the region without Iran.”

In his remarks, reported by the official IRNA news agency, Rafsanjani lambasted the West for insisting Iran join the alliance against IS.

He added: "You [the West] imposed sanctions on us, therefore we deem you as our enemies and will not side with you.”

Britain's prime minister has said that he does not believe the Islamic State can be defeated from the air alone, “troops on the ground” are needed. 

Speaking with Andrew Marr on the BBC on Sunday, David Cameron underlined that they should be Iraqi and Kurdish troops. 

“We are part of a large international coalition to degrade and ultimately destroy this organisation, but it can’t be done unless the countries where this organisation has grown up play their part to destroying it,” he told the BBC. 

As Qatar tries to convince critics that it’s cracking down on ISIL fundraisers within its borders, the US government has designated four men with ties to the Gulf country as terrorists for their alleged financial activities, reported Doha News. 

The accusations involve private individuals and not government officials. However, some of the men appear to have already had run-ins with local authorities for similar fundraising activities.

The refugee influx into Turkey shows no signs of abating with hundreds, and possible thousands of mainly Syrian Kurds trying to cross into Turkey on Sunday. 

The new arrivals, fleeing the IS onslaught as well as the intensifying US airstrikes, join between 130,000 - 160,000 other Syrian Kurds who have already fled north since IS stepped up its campaign to seize territory from Kurdish forces on 19 September. 

However, border controls have been getting tougher with many refugees forced to wait at the border where they were handed emergency supplies by aid workers. These pictures were taken at the Yumurtalik border crossing in Sanliurfa, south-western Turkey. 

NBC report shows vast majority of Americans expect that the US will end up sending ground troops into Iraq, despite repeated promises from the White House to not use boots on the ground. 

Watch the full report here: 

The US-led coalition destroyed three makeshift oil refineries in militant-controlled territory in Syria early on Sunday as it pressed efforts to deny Islamic State militants funding, a monitoring group said.

The coalition strikes hit close by the Turkish frontier, near the town of Tal Abyad just across the border fence from the Turkish town of Akcakale, the Syrian Observatory for Human Rights said.

Islamic State has launched a fresh offensive in order to regain the Kurdish populated city of Kobani in Syria, just across the border from Turkey, opposition groups in Syria claimed late on Saturday.

According to opposition groups in Syria and sources connected with IS, the militant group has launched comprehensive attacks late Saturday to seize the city of Kobani, the Anadolu Agency staff reported from the region.

British warplanes flew their first mission over Iraq on Saturday since being given parliamentary authority to strike at Islamic State jihadists, the Ministry of Defence in London said.

Royal Air Force Tornado GR4 combat jets, armed with Paveway IV laser-guided bombs, took off from Britain's RAF Akrotiri base on Cyprus.

In an operation that began before dawn, the jets were loaded with Paveways before taking off from the Mediterranean island.

Iran will attack the Islamic State inside Iraq if they advance near the border, ground forces commander General Ahmad Reza Pourdestana said in comments published on Saturday.

"If the terrorist group come near our borders, we will attack deep into Iraqi territory and we will not allow it to approach our border," the official IRNA news agency quoted Pourdestana as saying.

IS control a swathe of territory north of Baghdad, including in Diyala province, which borders Shiite Iran.

Toby Dodge, director of the LSE's Middle East Centre, has written for the International Institute for Strategic Studies criticising the tendency of politicians and commentators to talk about the troubles in Iraq and Syria in terms of the 1916 Sykes-Picot Agreement.

"Given the infamy of the Sykes–Picot agreement, it was no surprise that Lebanese Druze politician Walid Jumblatt declared its demise in June, going so far as to present Hassan Nasrallah, his colleague and the leader of Hizbullah, with a book that explained the genesis of the deal. But it is alarming that both academics and senior statesmen have also used the Sykes–Picot narrative in their accounts of the crisis in Syria and Iraq. The portrayal of the agreement as a catalyst for a century of Middle Eastern history is empirically and analytically unsustainable. It extrapolates from a brief moment in time, employing a snapshot that does not represent the wider socio-political dynamics that unfolded across the region during and after the First World War. This misuse of history may well lead to weak policy prescriptions."