(Photo : PATRICK SEMANSKY/AFP via Getty Images)
North Korea's Kim Jong Un's sister Kim Yo Jong arrives for the opening ceremony of the Pyeongchang 2018 Winter Olympic Games at the Pyeongchang Stadium on February 9, 2018. / AFP PHOTO / POOL / Patrick Semansky (

Kim Jong-un's sister, Kim Yo-jong, has issued a warning that the recent US-South Korean deal will lead to a "more serious danger". The warning comes after the US agreed to deploy nuclear-armed submarines to South Korea and involve Seoul in its nuclear planning to counter nuclear threats from North Korea. In return, South Korea agreed not to develop its own nuclear weapons.

Ms Kim holds a senior position in the Central Committee of the Workers' Party of Korea, and is reported to have influence on her brother. Referring to the agreement, she said that North Korea's nuclear deterrent "should be brought to further perfection" and warned that the move would "only result in making peace and security of North-East Asia and the world be exposed to more serious danger".

Under the deal, the US will send a nuclear-armed submarine to South Korea for the first time in 40 years, along with other assets, including nuclear-capable bombers. The two sides will also develop a Nuclear Consultative Group to discuss planning issues.

The US already has a treaty obligation to defend South Korea, and has previously pledged to use nuclear weapons if necessary. But some in South Korea have started to doubt that commitment and call for the country to pursue its own nuclear programme.

The nuclear threat posed by North Korea has been a cause for concern for both South Korea and the US. Pyongyang is developing tactical nuclear weapons that can target South Korea and refining its long-range weapons that can reach the US mainland.

President Biden hailed the deal, saying it would strengthen the allies' co-operation in deterring a North Korean attack. President Yoon also welcomed the agreement, describing it as an "unprecedented" commitment by the US to deter attacks and protect allies by using nuclear weapons.

However, China has warned against "deliberately stirring up tensions, provoking confrontation and playing up threats". It is clear that the situation in North-East Asia remains tense and complicated, and the recent US-South Korean deal will have far-reaching implications for the region.