Kim Jong-un says North Korea will grow nuclear arsenal ‘exponentially’ in surprise speech

North Korean leader Kim Jong-un said in a surprise speech on Monday that his country would exponentially increase its stockpile of nuclear weapons.

In a speech marking the 76th anniversary of the founding of North Korea, Mr Kim said there would be no limit on the expansion of the country’s military prowess, the official Korean Central News Agency reported on Tuesday.

It was Mr Kim’s first founding day speech since he assumed power in 2011, South Korea’s unification ministry noted.

South Korea’s defence minister warned in July that Pyongyang could be considering conducting a nuclear test close to the US presidential election in November.

“North Korea has completed preparations to conduct a nuclear test when a decision is made,” Mr Shin Wonsik said.

North Korea on Monday unveiled a new mobile missile launcher with 24 wheels for the first time, indicating a new intercontinental ballistic missile development.

Mr Kim had pledged a new policy to counter South Korea’s attempt to boost trilateral cooperation with the US and Japan after the three countries signed a military training pact in July.

“We are now perfectly carrying out the policy on building the nuclear armed forces, on increasing the number of nuclear weapons by geometrical progression,” Mr Kim said.

He reiterated that North Korea was “a responsible nuclear weapons state” and characterised the new policy as a “duty and right to existence.” A strong military presence was needed to face “the various threats posed by the United States and its followers”, he added.

This year, the leader said, the country “secured wonderful military strength by making important achievements in national defence studies and production”. He did not elaborate on the achievement.

Mr Kim said North Korea was facing a "grave threat" from a US-led nuclear-based military bloc in the region.

In Seoul, top defence officials of Japan, South Korea and the US met on Tuesday to reaffirm their commitment to strengthening trilateral cooperation and deterring North Korea‘s nuclear and missile threats, according to a joint statement released by the US State Department.

Cho Chang-rae, South Korea‘s deputy defence minister for policy, and his US and Japanese counterparts condemned Pyongyang’s recent diversification of nuclear delivery systems, tests and launches of multiple ballistic missiles.

They also agreed to hold a second trilateral military exercise, known as Freedom Edge, in the near term.

North Korea last month said it had moved 250 new mobile launchers for ballistic missiles capable of delivering nuclear warheads to the frontline. The military also unveiled its new suicide attack drones, something South Korea said was happening for the first time.