Japan's right to collective self-defense has been a topic of recent discussion between the U.S. and Japan.
In April, the White House published a joint statement with Japan asserting, in part, "The United States welcomes and supports Japan's consideration of the matter of exercising the right of collective self-defense."
The U.S. and Japan agreed they face "common security challenges," and resolved to strengthen and modernize their "security alliance."
Rodong Sinmun, the North's main newspaper, published a warning Tuesday that "Japan should keep in mind that it could be first hit by a fiery lightning in case of conflict."
The warning comes ahead of an expected press conference at which Japanese Prime Minister Shinzo Abe will reassert Japan's right to pursue collective self-defense.