North Korea has said the new U.S. sanctions targeting its leadership amount to a "declaration of war" and urge Washington to retract the measures immediately.
In a statement carried by the official Korean Central News Agency on July 7, the Foreign Ministry warned that Pyongyang will take "the toughest countermeasures to resolutely shatter the hostility of the U.S."
It did not elaborate on what this could entail.
Responding to the warning, the United States called on North Korea to "refrain from actions and rhetoric that only further raise tensions in the region."
This week, the United States sanctioned North Korean leader Kim Jong Un for the first time, with the Treasury Department naming him as directly responsible for human rights abuses in his country.
Ten other top North Korean officials were blacklisted.
The measures freeze any property the individuals have in the United States and prevent U.S. citizens from doing business with them.
North Korea had already been under an extensive sanctions regime for its nuclear activities, and the latest move is seen as an escalation of U.S. efforts to isolate the reclusive regime.