US President Donald Trump has signed a new order that boosts sanctions against North Korea over its nuclear weapons programme.
The US treasury has been authorised to target firms and financial institutions conducting business with the North.
The president also said China’s Central Bank had instructed other Chinese banks to stop doing business with Pyongyang.
It comes less than two weeks after the UN approved new sanctions against the country over its latest nuclear test.
Tensions have risen in recent weeks over the North’s continued nuclear and ballistic missile tests, despite pressure from world powers to stop.
Announcing a new executive order on Thursday, President Trump said the measures were designed to “cut off sources of revenue that fund North Korea’s efforts to develop the deadliest weapons known to humankind”.
He singled out the North’s textiles, fishing, information technology and manufacturing industries.
Donald Trump vowed to “totally destroy” the North if it posed a threat to the US and its allies, in his first address as US president to the UN General Assembly on Tuesday.
But North Korea’s top diplomat, Foreign Minister Ri Yong-ho, on Thursday likened Mr Trump’s comments to “the sound of a barking dog”.
Mr Ri is set to make a speech to the UN on Friday.
The General Assembly, which continues until Monday, is an annual event, bringing together leaders of the UN’s 193 member states.