Syria depression
In his speech in the US, Mr Osborne also defended the government's involvement in Libya - criticised by the foreign affairs committee earlier this month - and said governments should not be afraid of intervening in crises like Syria.
The Commons vote in 2013 against military action in Syria was "the single most depressing moment of my time to date in Parliament", he said.
Failing to intervene had led to the rise of the so-called Islamic State and a refugee crisis that had "fuelled the rise of extremism across Europe", and cost "hundreds of thousands of lives", he argued.