Britain has "got its mojo back" and stands alongside the United States in the fight to "reassert Western values", George Osborne has said.
Speaking in the US, the Chancellor said it was a "source of real pride" for him that MPs had overwhelmingly backed air strikes in Syria against Islamic State.
Mr Osborne said Britain, in partnership with the US, was taking the fight to IS by cutting off financing and tackling extremist ideology.
He told the Council on Foreign Relations think tank: "Britain has got its mojo back and we are going to be with you as we reassert Western values, confident that our best days lie ahead."
The Commons defeat Prime Minister David Cameron suffered over action in Syria against Bashar Assad's brutal regime in 2013 was a "striking moment", Mr Osborne said.
"The House of Commons did not agree with the proposition that David Cameron and myself and my colleagues in the Conservative leadership put forward and it was quite a striking moment," he told the think tank.
"It was a moment when Britain was unable to follow the lead asked of it by our Prime Minister and the government."
He added: "It is for me a source of real pride that actually a couple of years later the House of Commons has voted by a big majority to take part in the action already being directed against this terrorist organisation Isis or Daesh in Syria."
Mr Osborne said British air strikes were not the answer alone but insisted they would help degrade the jihadi organisation.