US President Barack Obama says he’s confident he can gather a broad international coalition to defeat Islamic State extremists in Iraq and Syria, following two days of talks at the NATO summit.

“I leave here confident that NATO allies and partners are prepared to join in a broad, international coalition,” Obama said on Friday after a meeting of the Western military alliance in Wales.

Following the beheading of two US journalists by the Islamic State, which has overrun swathes of northern Iraq and Syria, Obama said there was “unanimity” among NATO members that the group “poses a significant threat”.

Obama cautioned that “it’s not going to happen overnight”, but “we’re going to achieve our goal.

“We’re going to degrade and ultimately defeat ISIL (IS’s previous name) the same way we’ve gone after al-Qaeda,” he said.

US Secretary of State John Kerry will travel to the Middle East to seek support of regional powers, Obama said, insisting that Arab involvement was “absolutely critical”.

The president added: “Our hope is the Iraqi government is actually formed and finalised next week. That, then, allows us to work with them on a broader strategy.”

Kerry on Friday co-chaired with Britain a meeting of ministers from Australia, Canada, Denmark, France, Germany, Italy, Poland and Turkey in a bid to win support for the fight against IS.

IS caught the world by surprise when it made huge territorial gains and declared an Islamic “caliphate” in an area straddling Iraq and Syria.

The US has conducted more than 100 air strikes in northern Iraq in recent weeks, allowing Kurdish and Iraqi forces to regain ground lost to the jihadists.

Other countries have provided humanitarian assistance and intelligence, while Germany and France are providing military equipment to Kurdish fighters battling IS in northern Iraq.

Australia has assisted with airdrops of humanitarian aid and military equipment.

Kerry stressed Friday that there would be “no boots on the ground” in the US strategy against IS, but added that “there are many ways in which we can train, advise, assist, and equip”.

He urged allies to consider how they could contribute so the US could have a plan at the UN General Assembly meeting later this month.

European allies, while supportive of the US initiative, are proceeding with caution.

Britain has left the door open to air strikes in Iraq, but Prime Minister David Cameron played down the prospect of any immediate action.

“This will take time, patience and resolve,” he told reporters at the end of the summit.

“We will proceed carefully and methodically, drawing together the partners we need, above all in the region, to implement a comprehensive plan.”

President Francois Hollande said France was ready to join a coalition against IS militants in Iraq, but warned it would not commit to actions in Syria that might aid President Bashar al-Assad.

German Foreign Minister Frank-Walter Steinmeier stressed the effort was at an early stage.

“We are at the beginning in dealing with a group which nobody has a strategy to deal with in the long run,” he told reporters.

NATO Secretary General Anders Fogh Rasmussen said the military alliance was willing to help if there was a request from Baghdad, likely providing training and coordination with other countries’ efforts against IS.

“I think the international community has an obligation to do all it can to stop this dangerous terrorist organisation.”

Pressure to act has intensified since the executions by IS of two US journalists in videos showing a militant speaking in British English and threats that a British hostage would be next.