North Korea announced on Thursday that its constitution now officially labels South Korea as a "hostile" state. This is the first time North Korea has confirmed legal changes that leader Kim Jong Un had called for earlier this year. 

As "an inevitable and legitimate measure taken in keeping with the requirement of the DPRK Constitution which clearly defines the ROK as a hostile state," the nation demolished roads and railroads that connected it to the South this week, according to the official Korean Central News Agency. Days after Pyongyang's military vowed to "permanently" seal the border with the South, South Korea's military on Tuesday released video footage of North Korean soldiers dynamiting highly symbolic roads and railways connecting the two Koreas.

Relations between North and South Korea are at one of their worst points in years. In January, Kim Jong-un called South Korea his country's "principal enemy" and said North Korea is no longer interested in reunification. The army had taken "a measure to physically cut off the DPRK's roads and railways which lead to the ROK (South Korea)" on Thursday, according to KCNA.

The act was "part of the phased complete separation of its territory, where its sovereignty is exercised, from the ROK's territory". According to North Korea, parts of the main inter-Korean highways and railroads have "been completely blocked through blasting." 

"This is an inevitable and legitimate measure taken in keeping with the requirement of the DPRK Constitution which clearly defines the ROK as a hostile state," it added. Last week, the North Korea held a crucial meeting of its rubber-stamp parliament, marking the first indication that Kim's demands were reflected in the amendment of the nation's fundamental law.

The constitutional amendments were not covered in further detail in the report. Previously, relations between the North and South were not characterised as state-to-state relations but rather as a "special relationship" as part of a process aimed at eventual reunification, as per an inter-Korean accord in 1991. In a January speech, Kim demanded the constitutional amendment and threatened to go to war if the South violated "even 0.001 mm of our territorial land, air, and waters."

According to Seoul, the North Korean military has been refortifying the border for months by clearing land and placing new mines along it. The South says this is primarily done to stop Pyongyang's own citizens from defecting. Kim called a security meeting to oversee a plan of "immediate military action" in response to North Korea's recent accusations that Seoul had used drones to drop anti-regime propaganda leaflets on Pyongyang, the country's capital, according to state media on Tuesday.

Although Pyongyang has threatened to consider it "a declaration of war" if another drone is detected, Seoul's military has declined to comment after first denying sending drones north. While activists in the South have long used balloons to transport propaganda northward, some enthusiasts have also flown tiny, undetectable drones into the North.

According to individuals who spoke to local media, their devices were built from expanded polypropylene, which is similar to Styrofoam, rather than traditional drones made of metal. This allowed them to evade detection by both North and South Korean authorities. Drones have also been sent southward by North Korea; in 2022, five of Pyongyang's drones crossed the border, causing the South Korean military to send fighter jets and fire warning shots. However, the jets did not shoot down a single drone.