In March 2013, North Korea announced the abolition of all non-aggression pacts with South Korea. It also closed the border and the direct telephone line between the two Koreas.  North Korea also stated that it had the right to conduct a pre-emptive nuclear attack.  A UN spokesman said that the ceasefire agreement had been adopted by the UN General Assembly and could not be unilaterally dissolved by either North Korea or South Korea.  On March 28, 2013, the United States sent two stealth B-2 Spirit bombers to South Korea to participate in ongoing military exercises in the region, including dropping ammunition on a South Korean bombing room. It was the first non-stop B-2 tour from the United States to Korea.  Following this mission, North Korean media announced that they were preparing missiles ready to attack U.S. targets.  In May 2013, North Korea proposed to open negotiations for a peace treaty to replace the ceasefire agreement.   The signed ceasefire established a “complete cessation of all hostilities in Korea by all armed men” which should be imposed by the commanders of both sides.
However, the ceasefire is merely a ceasefire between the armed forces and not an agreement between governments to normalize relations.  No formal peace treaty has been signed and normalized relations have not been restored. The ceasefire founded the Military Dearcation Line (MDL) and the DMZ. The DMZ was agreed as a 4.0 km wide buffer zone between the two Korean nations.  The DMZ follows the Kansas Line, where the two sides clashed at the time of the signing of the ceasefire. The DMZ is currently the most defended national border in the world from 2018. [Citation required] Robert Einhorn, a former special adviser on non-proliferation and arms control at the U.S. State Department, proposed a more realistic approach to Washington.
Unicorn interpreted the solution of the denuclearization of the DPRK, advocated by North Korea. A reward should be given to Pyongyang, which completes every step from Pyongyang`s denuclearization to the complete denuclearization of its DPRK nuclear program. In short, this is a gradual or progressive approach to North Korea.  On December 11, at the meeting of the UN Security Council, the U.S. envoy to the United Nations, Kelly Craft announced that the United States.