LONDON (Reuters) - British Prime Minister Theresa May will appeal to NATO leaders on Thursday to unite to combat terrorism by addressing its root causes and the "propagation of poisonous ideology, particularly online".
After raising Britain's official terror threat level to "critical", the highest level, May will head to the NATO meeting in Brussels and thank the Western military alliance for its support following a suicide bombing attack in Manchester.
But she will also say that more needs to be done in the fight against terrorism and that the 28 NATO members are at the heart of such measures, bringing "valuable operational experience and tools" to deter attacks such as the one in Manchester, where a suicide bomber killed 22 people at a pop concert.
May, who will press for members to increase defence spending in line with NATO commitments, will cut short the next leg of her trip to Sicily, where the Group of Seven major powers will hold a two-day meeting, and instead leave on Friday.
"A strong, capable and united NATO is at the heart of the security of each and every one of our nations," she is expected to say, according to a senior government official.
"Our unity in responding to common threats is our most potent weapon."
Earlier, four senior European diplomats told Reuters that France and Germany would agree to a U.S. plan for NATO to play a bigger role in the fight against Islamic militants at a meeting with President Donald Trump, but that the move was symbolic.
The decision to allow the North Atlantic Treaty Organization to join the coalition against Islamic State in Syria and Iraq follows weeks of pressure on the two allies, who are wary of NATO confronting Russia in Syria and of alienating Arab countries who see NATO as pushing a pro-Western agenda.
The senior British government official said May would say that she believes "we must redouble our resolve to meet the threats to our shared society whether from terrorism or Russia".
She will use the Manchester attack, which she will describe as "a callous and cowardly act that was all the more sickening in the way it targeted innocent and defenceless children and young people", as an example of why the world needs to do more.
"Focussing on counter terrorism is not just about the military defeat of terrorists but addressing the root causes of terrorism and the propagation of poisonous ideology particularly online," the official said.
Reporting by Elizabeth Piper; Editing by Hugh Lawson