The Joint Chiefs said the missiles were fired eastward from South Hamgyong Province on the country's easy coast. Officials will continue to monitor the area "in case of additional launches," the JCS stated in a release.
South Korea's Defense Minister noted the weapons were of a type not previously seen.
A spokesperson for the US State Department informed the South Korean news agency that US officials "are aware of reports of a missile launch from North Korea" and that the matter is being monitored. However, the Japanese Ministry of Defense said no ballistic missiles had reached its territory or exclusive economic zone.
Another missile test not even a week ago, on July 25, saw DPRK fire two short-range ballistic missiles into the Sea of Japan from near Wonsan, to the south of Wednesday's test.
Following the Thursday test, US President Donald Trump said he was "not at all" worried, since his "relationship is very good with" North Korean leader Kim Jong Un. Pyongyang said the test was a message to the South to abandon its new weapons programs and shut down scheduled war games with the United States.
Earlier this year, Pyongyang resumed missile tests following a moratorium of over a year, as negotiations with Washington over disarmament and denuclearization stalled amid refusals to lower sanctions against the socialist country. Still, Kim has signaled a willingness to return to the negotiation table, even while sending the parallel message that he's unwilling to give up his country's only guarantee of safety without substantial movement from the US toward reconciliation and a mutual defusing of tensions on the peninsula.