President Donald Trump has announced a new order to help the US target people, companies and banks financing and facilitating trade with North Korea.
He also praised China for reportedly ordering banks to stop doing business with Pyongyang.
Mr Trump's actions follow his speech at the UN general assembly this week, when he escalated his rhetoric against North Korea amid a months-long crisis over Kim Jong Un's expanded missile testing programme.
He spoke of his own nation's "patience", but said that if "forced to defend itself or its allies, we will have no choice but to totally destroy North Korea".
Mr Trump said his new executive order would also disrupt other trade avenues for North Korea in efforts to halt its nuclear weapons programme.
He made the announcement on Thursday during a working lunch with Japanese Prime Minister Shinzo Abe and South Korean President Moon Jae-in.
Mr Trump said "tolerance for this disgraceful practice must end now".
He also saluted China's central bank for what he said was a move to stop its banks from trading with North Korea. That development was reported by Reuters on Thursday.
President Trump had earlier vowed the US will impose new sanctions on North Korea over its nuclear weapons build-up.
Mr Trump was speaking just days after he threatened to "totally destroy" the country if forced to defend the US or its allies.
The president placed the threat posed by North Korea at the centre of his debut at this week's UN general assembly, escalating his rhetoric against North Korea amid a months-long crisis over Kim Jong Un's expanded missile testing programme.
National security adviser H.R. McMaster said Thursday the new measures would stop "short of war."
Mr Trump was asked during a meeting on the sidelines of the United Nations about new punishments for the rogue nation and said new sanctions were coming.
Details were to be announced later on Thursday.
Vice President Mike Pence told Fox News Channel on Thursday: "We do not desire a military conflict.
"But the president has made it very clear, as he did at the UN this week, that all options are on the table and we are simply not going to tolerate a rogue regime in Pyongyang obtaining usable nuclear weapons that could be mounted on a ballistic missile and threaten the people of the United States or our allies."