US causing arms control collapse, says North Korea as it backs Russian call for pipeline blast probe

North Korea on Saturday blamed the US for what it said was the collapse of international arms control systems, adding that Pyongyang's nuclear weapons were a just response to ensure the balance of power in the region.

“The Korean peninsula is turning into the world's biggest powder keg and war practice field due to a military expansion scheme led by the US and its followers,” its foreign ministry said in a commentary carried by state news agency KCNA.

Recent moves by South Korea and Japan showed a military build-up by the US and its followers was crossing the danger line and this could not be tolerated, it added.

The comments follow the US and South Korea's announcement on Friday that they plan to conduct large-scale military exercises from March 13-23 to strengthen the allies' combined defensive posture, including focusing on what they called North Korean aggression.

North Korea says such joint military exercises are proof the US and its allies are hostile and bent on regime change in the north.

Meanwhile, North Korean state media weighed in on Saturday on allegations Western nations were involved in blasts that damaged Russia's undersea Nord Stream gas pipelines last year, in the latest move by Pyongyang to express support for Moscow.

Moscow has maintained, without providing evidence, the West was behind the blasts that damaged the pipelines in September and has called for an international investigation. Western officials have denied those accusations.

In an article carried by KCNA, international affairs critic Ahn Cheol-hyuk backed Russian calls for an impartial investigation, saying the world needs to be aware of the “vicious coerciveness, war and conspiracy manoeuvres of the US”.

Investigators from Sweden and Denmark — in whose exclusive economic zones the explosions occurred — have said the ruptures were a result of sabotage, but have not said who they believe was responsible.

North Korea has publicly supported Moscow since Russia invaded Ukraine a year ago and expressed support for Russia's proclaimed annexation of parts of Ukraine, which most countries have rejected.

The US has accused North Korea of providing weapons to Russia as well. Both Pyongyang and Moscow have denied that.

The ruptured Nord Stream pipelines are set to be sealed up and mothballed as there are no immediate plans to repair or reactivate them, sources familiar with the plans have told Reuters.