North Korea has accused rival South Korea of flying drones to its capital to drop anti-North Korean propaganda leaflets and threatened to respond with force if such flights occur again. North Korea's Foreign Ministry said in a statement Friday that South Korean drones were detected in the night skies of Pyongyang on Oct. 3 and Wednesday and Thursday this week.

The ministry accused the South of violating North Korea's "sacred" sovereignty and threatening its security, and said its forces will prepare "all means of attack" and respond without warning if South Korean drones are detected in its territory again.

"The safety lock on our trigger has now been released," the ministry said. "We will be prepared for everything and will be watching. The criminals should no longer gamble with the lives of their citizens."

While the rhetoric from Pyongyang on Friday did not specifically mention the country's nuclear arsenal, the North Korean regime headed by dictator Kim Jong Un has on multiple occasions in recent years alluded to using its atomic weapons if it deems its survival to be under threat.

South Korea's Joint Chiefs of Staff issued a statement saying it could not "confirm the truth of North Korea's claims" on Friday, adding that "all responsibility for the recent series of events lies with North Korea, which is carrying out despicable, low-level, and internationally shameful provocations."

"We strongly urge North Korea to refrain from rash actions and exercise self-restraint," the statement said. "If it threatens the safety of our people in any way, our military will resolutely and fiercely respond."

Tensions between the rival Koreas have escalated in recent months as North Korean leader Kim Jong Un has ramped up weapons tests and threats and South Korea has responded by strengthening its joint military exercises with the United States.

Since May, North Korea has also sent thousands of balloons carrying paper waste, plastic and other trash to drop on the South, in a bizarre psychological warfare campaign that worsened the animosity between the nations. The South's Joint Chiefs referred directly to those actions in its statement Friday when it spoke of the North's "shameful provocations."

On Wednesday, North Korea said it will permanently block its border with South Korea and build front-line defense structures to cope with "confrontational hysteria" by South Korean and U.S. forces.

North Korea's military said in a statement on state media that it will "completely cut off roads and railways" linked to South Korea and "fortify the relevant areas of our side with strong defense structures."

North Korea called its steps a "self-defensive measure for inhibiting war and defending the security" of the country and accused its rivals of "getting ever more reckless in their confrontational hysteria." North Korea cited what it called various military exercises in South Korea, the deployment of U.S. strategic assets and its rivals' harsh rhetoric.

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