Pyongyang recently unveiled a 5,000-ton destroyer-class vessel named Choe Hyon that some analysts said could be equipped with short-range tactical nuclear missiles.

Joint Chiefs of Staff (JCS) spokesperson Lee Sung-jun told reporters in South Korea that Russia may have given help with the warship.

"Looking at the weapons and equipment that were revealed, we believe that there is a possibility that they received technology, funds or assistance from Russia," Lee said.

"We are conducting a more detailed analysis."

North Korea confirmed on Monday for the first time it had deployed troops to Russia to support Moscow in its war in Ukraine.

The two countries also announced this week that they had started building the first road bridge linking the two neighbours.

North Korean leader Kim Jong Un oversaw the first day of a two-day weapons test of the vessel this week, according to Pyongyang's official Korean Central News Agency, during which he ordered officials to work on "accelerating the nuclear armament of the navy".

North Korea has said the destroyer, which it claimed is equipped with the "most powerful weapons", would "enter into operation early next year".

During the test, Kim said the North's ship-based firepower system was "effectively combined" with the "most powerful strike means including supersonic cruise missile, strategic cruise missile and tactical ballistic missile".

Lee said its deployment is likely to require more time.

"In the case of warships it takes several years to build and even after completion it takes additional time for them to become operational," the JCS spokesperson said.

"So although the Choe Hyon has been unveiled it seems likely that considerably more time will be needed for its (operational) deployment."