Samantha Power, the US ambassador to the United Nations, warned of a "dangerous" gulf emerging between the US and European defence spending, BBC reports.
In her interview to BBC Radio 4's Samantha Power told that cuts to defence budgets in Europe were "concerning" in the face of growing threats in the world.
On the occasion she had arrived in Brussels to encourage the leaders of NATO countries to meet the defence spending target of 2% of GDP.
On the contrary, Prime Minister David Cameron said the UK already met the NATO defence spending target and was also "due to meet it in the coming years".