Some scholars and policy analysts fear the North will use its nuclear arsenal to threaten South Korea and the US into making concessions.
These include ending joint US-South Korean Military drills and removing US troops from the South.
Senior analyst at the Sejong Institute think-tank, Cheong Seong-chang, said this can be used as a prelude to war with South Korea.
He said: “A North Korea with nukes will become more aggressive towards a South without nukes.”
Cheong Seong-chang argues the primary goal of North Korea’s nuclear weapons programme is to reunify the peninsula under Kim Jong-un.
South Korea’s Unification Minister Cho Myoung-gyon agrees.
He said he is alarmed at the increasing signals that North Korea sees nuclear weapons as a way to achieve its decades-old dream of unifying the Korean Peninsula.
The expert said: “Now that they are at the completion phase, they are coming up with new rhetoric that they haven’t been emphasising for a long time, like unifying the peninsula under a socialist regime.”
He warned against interpreting the two-month lull in North Korean missile launches as evidence as a de-escalation in tensions as the North has not returned dialogue.
It comes after a North Korean soldier tried to defect to the South this week.
The defector was shot by North Korean forces as he sprinted across the demilitarised zone and remains in a critical condition in a South Korean hospital.
South Korean and US forces did not return fire, but Mr Cho said this incident could have escalated into a full-blown conflict.
He added: “There is no way to convey our messages to the North during such incidents because all communication channels with the North have been cut off.”
Mr Cho dismissed the North’s aims of reunification as absurd.
He continued: “I can say strongly and clearly that the unification that North Korea wants will never happen.”
The comments come as satellite imagery shows North Korea is deep into an aggressive schedule to build and deploy its first ballistic missiles submarine.
Shipyard activity caught in satellite imagery shows evidence of an ongoing programme to create the country’s first operational ballistic missile submarine.
Speaking about earlier tests defence analyst Lance Gatling said: “The whole point of putting missiles into a stealthy platform like a submarine is to achieve tactical surprise, and this moves closer to that.”
Korea analysts North 38 uncovered movement at the Sinpo South Shipyard which indicated an accelerated process to complete the strategically key submarine.
Components including hull sections have been appearing on a ramp that enters an underground construction hall where it is suspected the SINPO-C submarine is being built.
The SINPO-C is the next step from the SINPO-class, which was an experimental submarine constructed to test the design.
A launch canister is also thought to have been identified on a testing platform from the images.