The US has imposed new expanded sanctions on North Korea over its nuclear program, weeks after it launched a long-range rocket.
North Korea has refused to stop its nuclear program and the bill was easily passed last week by Congress.
The sanctions attempt to cut off money North Korea needed to develop miniaturized nuclear warheads.
The US and China are negotiating over a UN Security Council resolution on new sanctions.
The sanctions freeze the assets of anyone doing business related to North Korea’s nuclear or weapons program or involved in human rights abuses.
The bill also allows for $50 million to support humanitarian programs and transmit radio broadcasts into North Korea.
North Korea recently fired a long-range rocket, which critics said was a test of banned missile technology. State television announced that North Korea had “successfully placed a satellite in orbit”.
The morning after that launch, Barack Obama said: “This is an authoritarian regime. It’s provocative. It has repeatedly violated UN resolutions, tested and produced nuclear weapons, and now they are trying to perfect their missile launch system.”
It came after North Korea’s fourth nuclear test in January. Analysts say Kim Jong-un is looking to appear powerful before his important Seventh Party Congress in May.
“The bill was the first one exclusively targeting North Korea, which was passed in an unusually expeditious fashion. We expect it to provide a platform for the US to take strong and effective measures [against North Korea],” said South Korea’s foreign ministry in a statement.
South Korea has said it will be discussing with the US the deployment of a missile defense system.