After both countries tested ballistic missiles hours apart, North Korean leader Kim Jong Un’s powerful sister criticized South Korean President Moon Jae-in and threatened the “complete destruction” of bilateral relations on Wednesday.

The missile launches highlighted a resumption of tensions between the rivals at a time when talks aimed at dismantling North Korea’s nuclear program are stalled.

Kim Yo Jong, Kim’s sister, chastised South Korean President Moon Jae-in for remarks made while watching his country’s missile tests, including the first of a submarine-launched ballistic missile. South Korea’s growing missile capabilities, according to Moon, will serve as a “sure deterrent” against North Korean provocations.

The tests came just hours after the South Korean and Japanese militaries reported that North Korea had launched two ballistic missiles into the sea.

In a statement carried by state media, Kim chastised Moon for referring to North Korean weapons demonstrations as a provocation, and threatened “complete destruction” of bilateral relations if he continued with his slander of North Korea.

She stated that North Korea is expanding its military capabilities for self-defense without a specific country in mind, and that South Korea is also expanding its military capabilities. North Korea has frequently accused the South of hypocrisy for introducing modern weapons while calling for talks to de-escalate tensions between the two countries.

The South Korean and Japanese militaries said North Korea’s two short-range ballistic missiles flew 500 miles before landing in the sea inside Japan’s exclusive economic zone, a concerning development despite the fact that they did not reach Japanese territorial waters. The last time a North Korean missile landed within that zone was in October of this year.

The launches came just two days after North Korea announced the launch of a newly developed cruise missile, the country’s first known missile test in six months. South Korea reported its first submarine-launched ballistic missile test just hours after the latest North Korean launches. The missile was launched from a submarine and hit a designated target as Moon and other top officials watched, according to Moon’s office. It was not specified how far the weapon flew.

According to experts, North Korea is developing its weapons systems in order to exert pressure on the United States in order to obtain relief from economic sanctions aimed at forcing the North to abandon its nuclear arsenal. For more than two years, US-led talks on the issue have been stalled.

According to observers, Moon’s administration, which has been actively pursuing reconciliation with North Korea, may have taken action to appear tougher in response to criticism that it is too soft on the North.

The rival nations are still technically at war because the 1950-53 Korean War, which pitted the North and its ally China against the South and US-led United Nations forces, ended in an armistice rather than a peace treaty.

It is unusual for North Korea to launch provocative missiles while China, its last major ally and largest source of aid, is engaged in a major diplomatic event. However, some experts believe North Korea may have used the timing to attract additional attention.

Kim Dong-yub, a professor at the University of North Korean Studies in Seoul, said the tests on Wednesday appeared to be of an improved version of a short-range missile that the North Koreans tested in March. He believes the weapon is based on Russia’s Iskander missiles, which are designed to fly at low altitudes, making them difficult to intercept by missile defense systems.

The international community wants North Korea to abandon its nuclear program and has long used a combination of sanctions threats and economic aid promises to try to persuade the North. However, negotiations have been stalled since 2019, when then-US President Donald Trump’s administration rejected the North’s demand for major sanctions relief in exchange for the decommissioning of an aging nuclear facility.

So far, Kim Jong Un’s government has rejected the Biden administration’s overtures for dialogue, demanding that Washington first abandon what it refers to as “hostile” policies. North Korea, on the other hand, has maintained its self-imposed moratorium on nuclear and long-range missile tests, indicating that it may not want to completely rule out the possibility of resuming the talks.