North Korea’s state media has broadcast a video footage of soldiers smashing bricks and twisting rods with empty hands and demonstrating combat skills.

According to the BBC, the troops demonstrated this skill at a defense exhibition in the capital, Pyongyang. North Korean leader Kim Jong-un and other leaders were present.

Soldiers were seen breaking bricks and tiles as well as pieces of broken glass and iron nails lying on beds and breaking concrete slabs in hand houses.

The exhibition also shows two soldiers bending iron rods around their necks. An army man has broken an iron chain with both his hands.

Leader Kim Jong-un smiled and enjoyed the show. With this, the North Korean army is “ready to defend the peace of the country with a thunderbolt” – that is what the enemies have been shown, according to the media.

Earlier on Tuesday, Kim Jong Un pledged to build an invincible military force, including weapons development, to deal with the enemy. Kim vowed to build the force in the face of hostile US policy.

Standing by North Korea’s largest missile, Kim said it was important for the United States to continue its weapons program in the face of hostile US policy and South Korea’s military development.

“Pyongyang is increasing its military size only to defend itself, not to start a war,” Kim said at an arms show on Monday.