UN Security Council is expected to meet on Tuesday
North Korea says a missile it launched over the weekend was a new type of long-range rocket that can carry a heavy nuclear warhead.
Pyongyang also claims the mainland United States is in its "sighting range for strike" following this latest test.
State media outlet KCNA claimed: "The test-fire [was] aimed at verifying the tactical and technological specifications of the newly-developed ballistic rocket capable of carrying a large-size heavy nuclear warhead."
Kim Jong Un - who is said to have overseen - claimed the test was aimed at "securing peace and stability in the Korean peninsula".
The launch was North Korea's fourth this year and landed in the Sea of Japan, near Russia.
The missile is believed to have travelled around 800 km.
The UN Security Council is expected to meet on Tuesday to discuss the latest North Korean test.
In a statement, the White House said Pyongyang has been "a flagrant menace for far too long".
"Let this latest provocation serve as a call for all nations to implement far stronger sanctions against North Korea," it said.
The test came only days after the election of a new liberal South Korean president.
Moon Jae-in has said dialogue and pressure must be used to ease tensions on the Korean peninsula and stop the North's weapons pursuit.