North Korean leader Kim Jong-un, at the eighth congress of the Workers’ Party, instructed the military to strengthen its nuclear weapons. He said that his country had upgraded its nuclear arsenal since November 2017, when it test-fired the Hwasong-15 intercontinental ballistic missile.

Kim’s remarks show that three years of denuclearization negotiations between the US and North Korea were just for show, and he has no intention of giving up nuclear weapons.

He instructed the military to make its nuclear weapons smaller and lighter. If the North develops tactical nuclear weapons, it will target them at South Korea. To deter the threat effectively, the South needs to be armed with the same weapons.

Kim defined the US as the North’s “foremost principal enemy.” He said that North Korea had completed the design of nuclear-powered submarines. Nuclear-powered subs are a strategic weapon that enables sneak attacks on the American mainland after approaching it because they can navigate underwater over long distances. If the subs are loaded with nuclear missiles, their threats will be hard to fend off.

The North Korean leader also vowed to develop supersonic weapons, which existing missile defense systems cannot intercept. If the North develops such weapons, important facilities in South Korea will be defenseless. Considering the North has improved ICBMs little by little, the South must not dismiss it as a bluff.Kim threatened that the inter-Korean relations may go back to the days before his first summit with Moon, depending on the attitude of the South Korean government, and demanded the South stop purchasing advanced weapons and suspend joint military exercises with the US.

President Moon Jae-in in his New Year’s address Monday said that “our will to meet with North Korea anytime, anywhere, even in a non-face-to-face way, remains unchanged.” He made no mention of the North’s military threats.

Lee Nak-yon, leader of the ruling Democratic Party of Korea, said that Kim seems to have given weight to dialogue in his speech at the Workers’ Party congress. Youn Kun-young, a Democratic Party lawmaker, said that if Kim visits South Korea, inter-Korean relations will take a long stride forward.

Even as the North is escalating its nuclear threats and vowing to develop new formidable weapons, Moon and the ruling party talk only of dialogue.

In March 2018, Chung Eui-yong, then director of Cheong Wa Dae’s National Security Office, visited the White House and convinced Trump that Kim was committed to denuclearizing his country. Moon and Trump held their respective summits with Kim. The US and South Korea downscaled their joint military exercises. But they turned out to have played into Kim’s hands. The Moon administration effectively helped Kim play for time to upgrade the North’s nuclear weapons.

For all the fierce criticism at home and abroad, the governing party passed legislation that criminalized the flying of propaganda leaflets via balloons toward North Korea. It made the law after Kim’s sister Kim Yo-jong said the Moon administration should “do anything about the balloons such as making a law.”

When the administration had yet to secure coronavirus vaccines, the unification minister said the South should share them with North Korea even if the country runs short of its own supplies. When North Korean soldiers shot a drifting South Korean government employee and burned him while he floated at sea, the Moon administration raised the unconvincing possibility of defection.

The South’s submissive attitude to curry favor with Kim only instigates him to act more boldly. The South cannot protect its security that way.

The North beefed up its military continuously despite economic distress, while the South thought only of dialogue and aid to the North. Along the way, it sacrificed military exercises with the US, suppressed freedom of expression through the flying of leaflets and even took a step to effectively neutralize anti-communist investigations.

A normal government would work out measures to counter the North’s new weapons. The South must take steps to beef up defense, including strengthening its alliance with the US, extending the range of its missiles and developing nuclear-powered submarines.

Dialogue is a sandcastle if military power does not prop it up.