South Korea said on Monday it had warned North Korea of a "strong" response if it provoked an incident similar to one last week that sparked an exchange of machinegun fire across their border.
The warning came as South Korean President Park Geun-hye reiterated on Monday her commitment to engage with the North, despite what she called "the dual nature" of ties, saying the "door was always open to dialogue".
South Korea said the North Korean firing was a "provocative act" that had violated the truce suspending their 1950-53 war and the complaint was reiterated in a notice the South sent the North late on Sunday.
"It is a stern warning of a strong response in the event of further provocation," South Korean Defence Ministry spokesman Kim Min-seok told a briefing.
The exchange of fire on Friday began after North Korea fired shots at balloons carrying leaflets sent towards the North by South Korean activists critical of the North's leadership.
North Korea has long criticised the leaflet drops as provocative and it has threatened to respond to them with force. But before Friday, it had never done so.
No one was hurt in the firing.
North Korea's state media said on Saturday that expected talks with the South to try to improve ties were in danger of being cancelled because authorities in South Korea had allowed the activists to float their balloons.
"The leaflet-scattering operation ... was a premeditated and deliberate politically motivated provocation perpetrated under the backstage wire-pulling of the U.S. and the South Korean authorities," the North's KCNA news agency said.
North Korea sent a high-level delegation on a surprise visit to the South on Oct. 4 and the two sides agreed to reopen dialogue, which has been stalled since February, late this month or early next.
Private groups in the South, often led by defectors from the North, cite their constitutional freedom of expression in releasing their balloons.
The South's Unification Ministry, which handles relations with the North, repeated on Monday it had no legal justification to stop the leaflet drops but said authorities may try to step in to prevent them on the basis of ensuring public safety.
