South Korea on Wednesday, January 13 fired 20 machine gun warning shots after a North Korean drone briefly crossed the rivals' border, officials said, the first shots fired in a Cold War-style standoff between the Koreas in the wake of the North's nuclear test last week, the Associated Press reports.

The North Korean drone was flying dozens of meters south of the border and turned back to the North after the South fired the shots, South Korean defense and military officials said, requesting anonymity because of office rules. The shots did not hit the drone.

North Korean drone flights across the world's most heavily armed border are rare, but have happened before.

North Korea has in recent years touted its drone program, a relatively new addition to its arsenal. In 2013, state media said North Korean leader Kim Jong Un had watched a drone attack drill on a simulated South Korean target.

Since Friday, South Korea has been blasting anti-Pyongyang propaganda and K-pop songs from huge speakers along the border. The North, which calls the broadcasts an act of war meant to threaten its system of government, is using speakers of its own in an attempt to keep its soldiers from hearing the South Korean messages.

Seoul said Wednesday that thousands of North Korean leaflets, likely sent across the border by balloons, have been found in the South. Some described South Korean President Park Geun-hye and her government as "mad dogs."

North Korea's propaganda machine is using the nuclear test to glorify Kim's leadership and describing it as a necessary step to fight against what it calls a U.S.-led attempt to overthrow the North's system.