According to Pentagon spokesman Captain Jeff Davis, the launch occurred at about 10:45 ET (14:45 GMT).
"I can confirm that we detected a launch of a ballistic missile from North Korea," Capt. Jeff Davis confirmed. "We are assessing and will have more information soon."
Earlier today, Japanese media reported that North Korea "appeared to have fired a missile."
Soon after the initial report, the South Korean military confirmed DPRK's missile launch. South Korean President Moon Jae-in convened an emergency meeting of his national security team in the early hours of Saturday.
According to Japanese Chief Cabinet Secretary Yoshihide Suga, the North Korean missile flew for about 45 minutes.
On July 4, North Korea announced it had successfully launched its first intercontinental ballistic missile, saying it traveled 580 miles and reached an altitude of 1,740 miles during its 39-minute flight before accurately hitting a targeted area in the Sea of Japan. The test immediately prompted sharp criticism from the international community.
Following the launch, the Russian Defense Ministry disputed Pyongyang's claim, saying the missile's flight parameters indicated it reached an altitude of 535 kilometers (332 miles) and traveled 510 kilometers before falling in the central Sea of Japan. However, US officials believe that Pyongyang had successfully launched an ICBM for the first time.