SEOUL, South Korea — South Korea on Friday proposed military talks with North Korea to resolve disagreements about where their border lies and prevent accidental clashes in frontline areas, seeking to ease tensions after recent landmine blasts injured three South Korean soldiers.

It’s unclear whether North Korea will agree to talks. Authoritarian leader Kim Jong Un has taken a hard line toward Seoul and has suspended virtually all dialogue and cooperation with the South in recent years. Meanwhile, North Korea has been adding mines, barbed wire fences, tactical roads, anti-tank walls and other fortifications to what’s already one of the world’s most heavily armed borders.

South Korea’s military has said North Korean soldiers crossed the border’s military demarcation line 50 times this year during fortification work, and that it responded with warning shots and broadcasts.

The South’s military made a proposal for similar talks in November that was ignored by the North. Seoul has shown greater urgency to ease tensions after the Sept. 21 mine blasts at the border, which the South’s military concluded were caused by North Korean mines planted south of the military demarcation line.

“Our Ministry of National Defense officially proposes to North Korean authorities that South-North military talks be held to mutually confirm the exact location of the ground military demarcation line between the South and the North, discuss the restoration of military communication lines, and discuss measures to prevent accidental clashes in border areas,” Kim Hong-Cheol, South Korea’s deputy minister for defense policy, said in a televised statement Friday.

He said the South was also open to three-way talks involving the U.S.-led United Nations Command.

The proposal came days after Kim Jong Un’s powerful sister visited front-line areas where North Korean troops are reinforcing the border. During her visit, she renewed a threat to retaliate against any South Korean provocation aimed at the fortification work.

Kim Yo Jong also said the North planned to activate border loudspeakers for anti-Seoul propaganda broadcasts, a psychological warfare tactic long used by both Koreas, and has placed unspecified “new counter means” on alert along the border. She blamed the South for firing warning shots and broadcasting warnings toward North Korean soldiers fortifying the border under what she called a false pretext that they were crossing the demarcation line.

South Korean officials have said North Korea’s recent border activities have highlighted the Koreas’ disagreement over exactly where the military demarcation line lies. The line was drawn up under the 1953 armistice that stopped the fighting of the Korean War, and some decades-old boundary markers have been lost over time.

However, South Korean Defense Minister Kang Shin-chul has said the location of last month’s mine blasts was not in a disputed area. The North has denied responsibility for the incident and dismissed Seoul’s demand to apologize and remove its remaining mines.

Kim Hong-Cheol, the South Korean military official, said leaving the dispute over the military demarcation line unresolved would increase the risk of accidental clashes because troops from both sides act on their own understanding of the line. “The recent increase in North Korean activities along the military demarcation line, as well as our warning broadcasts and warning shots, is also related to this situation,” he said.

While visiting front-line areas with Kim Yo Jong on Wednesday, North Korean Army Marshal Pak Jong Chon denied that North Korean soldiers were breaching the border during fortification work, saying “our army knows where our borderline is better than any others.”

He accused the South of making “deliberate, premeditated and absurd” claims to shift blame over the rising tensions and threatened an “overwhelming response” to South Korean provocations.