SEOUL (AFP) -- South Korea’s 
military said Monday it was “fully ready” to respond after North Korea ordered troops on the border to prepare to fire in an escalating dispute over drone flights to Pyongyang.
The nuclear-armed North has accused Seoul of flying drones over its capital to drop propaganda leaflets filled with “inflammatory rumors and rubbish”, and warned Sunday that if another drone was detected, it would consider it “a declaration of war”.
Seoul’s military previously denied it was behind the flights, with local speculation centered on activist groups in the South, which have long sent propaganda and U.S. currency northwards, typically by balloon.
But the North insists Seoul is officially to blame, announcing late Sunday it had told eight artillery brigades already on war footing “to get fully ready to open fire”, and reinforced air observation posts in Pyongyang.
“Our military is closely monitoring the situation and standing fully ready for the North’s provocations,” Lee Seong-joon, a spokesman for the South’s Joint Chiefs of Staff (JCS), told a press briefing.
Pyongyang claims propaganda drones have infiltrated the capital’s airspace three times in recent days, with leader Kim Jong Un’s powerful sister threatening a “horrible disaster” unless they stop.
In a statement early Monday, Kim Yo Jong said the drone flights were “an unpardonable, malicious challenge to our state”.
She has issued three similar back-to-back statements, calling on South Korea’s military to come up with measures to prevent a recurrence of violations of North Korean airspace.
The JCS on Monday neither confirmed nor denied that Seoul’s military was responsible for sending drones across the border, instead calling the North’s claim “shameless”.
Seoul’s military said Monday that the North appeared to be preparing to carry out explosions at roads connected to the South, days after Pyongyang said it would seal the border.
Last week, the North’s Korean People’s Army (KPA) announced the measure will “completely separate” North Korea’s territory from the South.
South Korean JCS spokesman Lee said it was possible the road blasts would take place “as early as today”.
North Korea has been bombarding the South with trash-carrying balloons -- retaliation, it says, for propaganda launched by activists in the South.