The unspecified test took place from 10.41 p.m. to 10.48 p.m. on Friday night at the Sohae Satellite Launching Ground, better known as the Dongchang-ri site, Yonhap News Agency reported citing the North's official Korean Central News Agency (KCNA) as saying.
It did not say what was tested.
"The research successes being registered by us in defence science one after another recently will be applied to further bolstering up the reliable strategic nuclear deterrent," the KCNA said.
"Our defence scientists were honoured to receive warm congratulations from the Central Committee of the Workers' Party of Korea on the spot," it added.
Friday's test came about a week after the North conducted what it called "a very important test" at the satellite launch site on December 7, sparking concern that the communist nation could be preparing to launch a long-range rocket.
South Korea has confirmed that the North tested a rocket engine last week.
The Friday night test also came a day before US top nuclear envoy Stephen Biegun's planned visit to Seoul in an apparent bid to keep up the dialogue momentum with the North, said Yonhap News Agency.
Speculation was growing that he could visit the inter-Korean border truce village of Panmunjom for possible contact with North Korea.
The North has used the Dongchang-ri site to test rocket engines and launch vehicles to deliver satellites, and such technology could be diverted to develop and launch long-range weapons.
In March 2017, North Korea successfully tested a new high-thrust engine at the station, which was employed to launch ICBMs, such as the Hwasong-14 and Hwasong-15, later that year.
Amid stalled denuclearization talks, North Korea has carried out a series of weapons tests in recent months mostly involving short-range missiles.
The latest one took place on November 28, when Pyongyang tested its super-large multiple rocket launcher.
( With inputs from IANS )