Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, claimed that a U.S.-South Korea agreement this week over the need to strengthen South Korean security will make matters worse, according to official media KCNA on Saturday.

Kim claimed that as a result, North Korea is persuaded it needs to continue working on a “nuclear war deterrent”. The statement gave no further details.

Kim’s statement is North Korea’s first comment on the meeting, and suggests its cycle of military shows of force and weapons development will continue.

U.S. President Joe Biden and South Korean President Yoon Suk Yeol met this week, with the United States pledging to give South Korea more insight into its nuclear planning over any conflict with North Korea amid anxiety over Pyongyang’s growing arsenal of missiles and bombs.

A U.S. Navy nuclear-armed ballistic missile submarine (SSBN) will also visit South Korea for the first time since the 1980s, to help demonstrate Washington’s resolve to protect the country from a North Korean attack.