South Korean activists release balloons carrying anti-North Korea leaflets, from a park near the inter-Korea border in Paju, north of Seoul, in October 2014. PHOTO: AFP

When North Korea conducted its fourth underground nuclear test in early January this year, South Korea responded by sending balloons carrying propaganda across the border.However, little did South Koreans know that it would take the propaganda warfare to an unprecedented level.Within a week, the North responded by floating balloons into the South filled with used toilet paper, cigarette butts, and propaganda messages.The balloons fitted with a timer and a small explosive device are designed to drop their payload in the South and spread crude propaganda messages.While some of the propaganda messages read, "Stop the anti-North psychological warfare broadcasts that light the fuse of war," others encouraged locals to, "Knock out the gang of [South Korean leader] Park Geun-hye."When balloons initially appeared, South Korean authorities feared that the balloons might be filled with biochemical substances. "We were concerned that North Korea could have sent biochemical substances to harm our people, but after analysing the contents it was just trash", a South Korean military official said.Tensions between the two Koreas escalated once again after North Korea on January 6 claimed that it had carried out a “successful” hydrogen bomb test.International condemnation was swift with neighbours South Korea and Japan decrying a gross violation of UN Security Council resolutions, while the White House said it was still studying the precise nature of the apparent test and vowed to “respond appropriately”.“The republic’s first hydrogen bomb test has been successfully performed at 10:00am,” North Korean state television announced. “With the perfect success of our historic H-bomb, we have joined the rank of advanced nuclear states,” it said, adding that the test was of a miniaturised device.Earlier in December, North Korean leader Kim Jong-Un suggested Pyongyang had already developed a hydrogen bomb. The claim was questioned by international experts and there was continued scepticism over Wednesday’s test announcement.The article originally appeared on The Telegraph