North Korea on Friday accused South Korea of flying drones over its capital and dropping anti-North Korean leaflets, saying the incursion crossed the "red line" and could lead to armed conflict, according to reports.
South Korea's Joint Chiefs of Staff said it couldn't confirm the allegations but noted that North Korea has been sending balloons toting bags of trash into South Korean airspace, Reuters reported.
North Korea blamed its southern rival of flying the drones and releasing leaflets over Pyongyang last Thursday and on Wednesday and Thursday of this week.
"Smear leaflets, run through with inflammatory rumors and rubbish tarnishing the national sovereignty and dignity of the DPRK and malignantly hurting its socialist system, were scattered in the central part of the capital city," North Korea's foreign ministry said in a statement, reported by state-run media KCNA.
It referred to North Korea by its official name, the Democratic People's Republic of Korea.
South Korea "should immediately stop such irresponsible and dangerous provocation that may cause an armed conflict and lead to a war between the two sides," North Korea said, accusing Seoul of violating its sovereignty.
"Criminals should no longer gamble at risk for the lives of their people," it warned.
South Korea's Joint Chiefs of Staff advised the North to "exercise restraint and not act recklessly."
"If the safety of our citizens is threatened in any way, our military will respond with stern and thorough retaliation," it said, the Associated Press reported.
Seoul has threatened to take "decisive military action" if anyone is killed by the trash balloons North Korea has launched across the border.
President Kim Jong Un's regime has sent more than 5,000 balloons into South Korea since May, causing fires and disrupting flights.