The Islamic State's brand of extremism needs to be snuffed out, according to US President Barack Obama.
Speaking at a fundraising event in Baltimore he said it was a "sobering time" but the threat from Islamic State has focused the world's attention on the need to "ultimately snuff out this particular brand of Islamic extremism that really has no place in the 21st century."
He added that he is leading an effort to form a coalition of Western allies and Gulf Arab states to take on the extremist group.
Downing Street has said David Cameron supports Barack Obama's planned air strikes against Islamic State militants in Syria but Britain is "not at the stage" of deciding whether to taking part in the military action.
The US President announced in a televised speech the military plans to "degrade and ultimately destroy" IS through air strikes in Syria and an expansion of strikes in Iraq.
Nearly 500 US troops will be sent to Iraq to assist its security forces while Mr Obama also wants Congress to approve a plan to train and arm Syrian rebel groups fighting IS.
The Prime Minister's official spokesman said:
I think you have seen our approach for the support that the US has already been taking.
As to future decisions that are taken, we will work with them and the other regional partners on the ground.
As to what each country together, how they work in complement with each other, those are decisions for further down the line but I think you will continue to see unity of approach.
The Foreign Secretary has said Alan Henning's family are "going through hell" after his capture by Islamic State militants.
Speaking to reporters in Paris, Philip Hammond said the Government was doing what it could but there were "limitations" to what they could do to help Mr Henning.
"We understand that Mr Henning's family are going through hell at the moment - it's a terrible time for them - we are doing everything we can to protect him," he said.
"They understand, because we've explained to them in detail, the limitations of our abilities and that we are dealing with a very barbaric organisation whose values are completely different to ours," Mr Hammond added.
The Foreign Secretary says the UK will play "a leading role" in the international effort against the Islamic State (IS) terrorist group.
Philip Hammond said today's meeting of 30 different governments was a "very positive step forward" in the process of building a coalition to take action against IS.
Alan Henning was captured while on a humanitarian aid mission. He appeared in a video released at the weekend which also showed the apparent beheading of another Briton, David Haines.
Friends of Mr Henning say he's a kind man who was only in Syria to do good.
Meanwhile, special prayers were said for him at a mosque in Rochdale with muslims there utterly condemning the actions of Islamic State. Our correspondent Elaine Willcox has this report.
Imam Shabbir Sialvi says the whole community condemn the actions of the Islamic State and today prayers were said for Salford taxi driver Alan Henning.
Orlando Napolitano has told ITV News that Alan used to come into his cafe twice a day. He last saw him in December just before he left for Syria - he says he was a nice guy who just wanted to help others.
There must be a "global response" to the "global threat" posed by Islamic State (IS) extremists, French president Francois Hollande has said.
Speaking at the start of a conference in Paris aimed at coordinating a strategy against IS, Hollande said: "What is the threat? It is global so the response must be global."
Manchester should be given income-tax raising powers and complete control of spending within five years as a blueprint for granting full devolution to English cities, a think tank said.
Scotland's independence referendum - and the extensive new powers promised even in the event of a No vote - has refocused attention on local powers in the rest of the UK, including England.
ResPublica said a Greater Manchester Combined Authority, with an elected mayor and assembly as in London, should first be given power over property taxes and then income taxes and the right to reinvest savings to increase revenue.
The new authority would also be expected to commit to devolving further to localities within its area, according to the "Devo Max - Devo Manc" report.
Director Phillip Blond said: "For decades we've watched England's cities sliding into decline. This is why England needs devolution.
"Financial freedom must come to Greater Manchester. Its population is bigger than Northern Ireland's. Its economy is bigger than Wales. And it has a higher growth rate than Scotland. This is why it should be able to set its own taxes. It should have an elected Mayor.
"These plans outlined in today's report, will allow it to turn its fortunes around, lifting the population out of the doldrums. This is a blueprint for independence for cities in England."
Lord Peter Smith, chair of the Greater Manchester Combined Authority - which brings together the areas 10 existing authorities - said: "We welcome the broad thrust of this independent analysis which makes a case for total devolution to city regions on a scale that recognises the game-changing potential to both reduce public spending and boost growth."
Islamic State (IS) have "hijacked the name of Islam", according to a Shia sheikh, who is campaigning for the media and public to change the name they use for the terrorist group.
Sheikh Mohammed Al-Hilli told Good Morning Britain: "The goal is to get them to understand that this is nothing to do with Islam what so ever. It's barbaric and it's against humanity."