Clinton told journalists the sanctions were not aimed at the people of North Korea, and were designed to prevent Pyongyang from buying or selling weapons and buying luxury goods.
“They are directed at the destabilising, illicit and provocative policies pursued by that government,” she said.
The US and South Korea, citing the findings of a multinational investigation, accuse the North of torpedoing the warship Cheonan, killing 46 people, in March.
Few details were given about the sanctions. RFI’s Daniel Finnan spoke to Korea analyst Kerry Brown, from the London-based think-tank Chatham House, about possible sanctions. Brown says it is difficult to find new pressure points to put on the regime.
“The leadership has some financial assets in Macao, Switzerland and in Europe. So I think part of the present sanctions will include freezing assets, and continuing to try to starve the regime of Pyongyang of technical assistance for anything associated with its weapons programme.”
“But restrictions on weapons technology are already extremely tough so it will be probably peripheral technology,”
Clinton arrived in Seoul, the South Korean capital on Wednesday, after visiting the demilitarised zone between the two regional foes, with US Defense Secretary Robert Gates.
"There has been some indication over the last number of months, that as the succession process gets under way in the North, that there might be provocations particularly since the sinking of the Cheonan," Gates said.
"So I think it is something that we have to look at very closely, we have to keep in mind and be very vigilant."
Aging leader Kim Jong-Il, 68, is reported to be preparing to name his youngest son as eventual successor.
The sinking has sharply raised tensions on the peninsula, 60 years on from the start of the 1950-53 Korean War.