North Korea has vowed a "physical response" to measures taken by the United States against the Communist-ruled state following the sinking of a South Korean warship blamed on the North.
Washington earlier this week announced new sanctions against North Korea, targeting its ruling elite.
The United States and South Korea have also announced joint naval exercises due to begin on July 25.
An international probe held the North responsible for the sinking of the South Korean warship in March which killed 46 South Korean sailors -- but the North denies any involvement.
Ri Tong Il, a spokesman for the North Korean delegation at a summit of the Association Of South-East Asian Nations (ASEAN) in Hanoi on July 23, said this weekend's naval exercises will violate the North's sovereignty.
U.S. Secretary of State Hillary Clinton, also speaking at the ASEAN summit, accused North Korea of embarking on a "campaign of provocative, dangerous behavior."
Participants in the forum include the 10 nations of ASEAN, as well as the United States, European Union, China, Russia, Japan, and other countries.
compiled from agency reports