Tensions on the Korean peninsula have escalated after Kim Yo-jong, sister of North Korean leader Kim Jong-un, warned that new military firepower units had taken positions along the heavily fortified border with South Korea. Visiting frontline troops, she threatened retaliation if South Korean warning shots endangered North Korean personnel or territory. Seoul says its soldiers have fired warning shots when North Korean troops crossed the border during fortification work. The latest confrontation follows September landmine explosions which injured three South Korean soldiers, which Seoul blamed on North Korean devices. Pyongyang denies responsibility and has threatened further retaliation. Since April 2024, North Korea has strengthened its border defences with additional landmines, barbed wire and anti-tank barriers. Meanwhile, North Korean state media released photographs apparently showing Kim Jong-un attending a public event, following unsubstantiated rumours about his death. The growing military confrontation raises concerns about accidental escalation along one of the world's most heavily armed borders.