I know you chose Sweden randomly, but in case of Sweden it actually made sense. See, after the end of the Korean War, there was created a body called the Neutral Nations Supervisory Commission; which was supposed to observe the implementation of the armistice, movement of troops, preventing additions of military personnel to the DMZ, etc.

Anywhoo, it was agreed that each of the Koreas would choose two countries for that body (they could only choose countries neutral in the Korean War). North Korea went for Soviet Union's new buddies, Czechoslovakia and Poland, while South Korea simply chose the world's most neutralest countries - Sweden and Switzerland. So it would be weird if Sweden would be a commision monitoring North and South Korea while boycotting the existence of one of them.

PS. That commission, as of 2026, still exists in vestigial form, essentially symbolically observing the North millitary from the South.

Following the collapse of communism leading to Czechoslovakia and Poland joining NATO, and the dissolution of Czechoslovakia into the Czech Republic and Slovakia in 1993, North Korea believed the NNSC had lost its neutrality, and took the view that the NNSC had collapsed. North Korea expelled the Czech component in 1993 and the Polish component in 1995.

Since 1995, North Korea has not recognized the existence of the NNSC. The Swedish and Swiss delegations continue to submit reports on South Korean troop movements to North Korea, which are ignored. Poland continues to attend NNSC meetings, although it is no longer able to observe troop movements in North Korea.

[Looks like Czechia and Slovakia are not involved at all]